President Trump and his top aides demanded on Wednesday that Ukraine accede to an American-designed proposal that would essentially grant Russia all the territory it has gained in the war, while offering Kyiv only vague security assurances.

The American plan, which would also explicitly block Ukraine from ever joining the North Atlantic Treaty Organization, was rejected by President Volodymyr Zelensky of Ukraine, whose long-running dispute with Mr. Trump broke into the open two months ago in the Oval Office. The proposal also appears to call for the United States to recognize Russia’s 2014 takeover of Crimea, a region of Ukraine.

“There is nothing to talk about,” Mr. Zelensky said. “This violated our Constitution. This is our territory, the territory of Ukraine.”

Mr. Trump shot back on social media that the Ukrainian president was being “inflammatory” and said he would only “prolong the ‘killing field.’”

Mr. Trump suggested the proposal was on the verge of acceptance by President Vladimir V. Putin of Russia. “I think we have a deal with Russia,” he told reporters at the White House. The problem, he suggested, was Mr. Zelensky.

“I thought it might be easier to deal with Zelensky,” he said. “So far it’s harder.”

Vice President JD Vance struck a similar theme while traveling in India.

He said the United States would “walk away” from the peace process if both Ukraine and Russia refused to accept the American terms. But Mr. Zelensky was clearly the target.

“We’ve issued a very explicit proposal to both the Russians and the Ukrainians, and it’s time for them to either say yes or for the United States to walk away from this process,” Mr. Vance told reporters. “The only way to really stop the killing is for the armies to both put down their weapons, to freeze this thing and to get on with the business of actually building a better Russia and a better Ukraine.”

It was not clear whether the U.S. announcements were part of a pressure campaign to force Mr. Zelensky to make territorial concessions or whether they were designed to create a pretext for abandoning American support for Ukraine.

But the United States is essentially settling on a deal that favors the aggressor in the war, one that forces Ukraine to accept the forcible rewriting of its border and give up its hope of eventually joining NATO, as other former Soviet republics have.

European allies, who in recent weeks have been promising more military and economic support for Mr. Zelensky, have charged that Mr. Trump is essentially switching sides in the war, and that his real goal is to cast Ukraine aside and to find a way to normalize American relations with Moscow. Mr. Trump and his top aides have already begun discussing the prospect of lifting sanctions on Russia, and striking energy and mineral deals with Mr. Putin.

Whatever Mr. Trump’s motives, what happened on Wednesday signaled the possible abandonment of the American commitment to Mr. Zelensky that the United States would never engage in talks that excluded the country from determining its own fate.

While the United States did not release a text of its proposal, European officials who have seen it say that under its terms the United States would recognize Crimea — which Mr. Putin seized illegally in 2014 — as Russian territory. While the peninsula was part of Russia for hundreds of years, it was given to Ukraine by the Soviet leader, Nikita Khrushchev, nearly seven decades ago.

In his social media post, Mr. Trump said he was not asking Mr. Zelensky to recognize Crimea as Russia, even though the U.S. plan would call for Washington to do so.

“Nobody is asking Zelenskyy to recognize Crimea as Russian Territory but, if he wants Crimea, why didn’t they fight for it eleven years ago when it was handed over to Russia without a shot being fired?” Mr. Trump wrote.

Just three years ago, Marco Rubio, then a senator and now Mr. Trump’s secretary of state, cosponsored an amendment to prohibit the United States from ever recognizing any Russian claim of sovereignty over parts of Ukraine that it has seized.

“The United States cannot recognize Putin’s claims or we risk establishing a dangerous precedent for other authoritarian regimes, like the Chinese Communist Party, to imitate,” he said at the time, an allusion to Taiwan.

Now Mr. Rubio has become a defender of Mr. Trump’s approach, even if Ukraine has to surrender 20 percent of the country to Mr. Putin and give the Russian leader most of his war goals.

Mr. Trump has been taking other steps to mollify Mr. Putin. He has dismantled or neutralized units in the State Department and the Justice Department charged with collecting evidence of possible war crimes committed by Russia, including the killings of civilians in Bucha, outside of Kyiv, soon after the Russian invasion.

It is unclear what happens if Mr. Zelensky refuses to relent. Mr. Trump has suggested he would simply wash his hands of the peace effort — one he once said was solvable in 24 hours — and, in Mr. Rubio’s words, “move on.”

Already, the United States has limited its weapons shipments to Ukraine, although some weapons are still going through. And U.S. intelligence sharing has resumed, after a temporary pause to pressure Kyiv to come to the negotiating table.

But Mr. Trump continued his effort to belittle the Ukrainian leader, who was once cheered by lawmakers of both parties who likened him to Churchill. “The situation for Ukraine is dire,” Mr. Trump wrote. “He can have peace, or he can fight for another three years before losing the country.”

On Wednesday afternoon, Yulia Svyrydenko, the Ukrainian economy minister, also vowed that her country “will never recognize the occupation of Crimea.” Writing on X, the social media site, she said that “Ukraine is ready to negotiate — but not to surrender. There will be no agreement that hands Russia the stronger foundations it needs to regroup and return with greater violence.”

Mr. Vance told reporters in India that under the American proposal, “We’re going to freeze the territorial lines at some level close to where they are today.”

“The current lines, or somewhere close to them, is where you’re ultimately, I think, going to draw the new lines in the conflict,” he added. “Now, of course, that means the Ukrainians and the Russians are both going to have to give up some of the territory they currently own.”

A Kremlin spokesman on Wednesday welcomed Mr. Vance’s remarks.

“The United States is continuing its mediation efforts, and we certainly welcome those efforts,” the spokesman, Dmitri S. Peskov, said. “Our interactions are ongoing but, to be sure, there is a lot of nuances around the peace settlement that need to be discussed.”

The aggressive push for a deal by Mr. Trump’s administration is a blow to European leaders, who have spent weeks attempting to shore up Ukraine’s position by brokering peace talks with the United States. The first effort convened last week in Paris and another session was set to start Wednesday in London before Mr. Rubio announced that he would no longer attend.

Mr. Rubio’s decision to cancel caught the British government off guard, according to a British official who said that David Lammy, the foreign secretary, had fully expected the secretary of state in London on Wednesday.

Lower-level diplomats from Britain, France, Germany, Ukraine, and the United States still gathered for technical talks. But the absence of Mr. Rubio or Steve Witkoff, Mr. Trump’s chief negotiator with Russia, renewed fears that Ukraine and Europe were being marginalized as the Trump administration seemed to be working primarily with Russia.

Mr. Witkoff is scheduled to be in Moscow later this week, Karoline Leavitt, the White House press secretary, said Tuesday.

Andriy Yermak, the Ukrainian president’s chief of staff, arrived in London on Wednesday morning for the scaled-back talks, along with his country’s ministers of defense and foreign affairs.

“Despite everything,” he wrote on X, the social media platform, after arriving, “we continue working for peace.”

Reporting was contributed by Ségolène Le Stradic from Paris; Steven Erlanger and Anton Troianovski from Berlin; Nataliya Vasilyeva from Istanbul; Andrew E. Kramer from Kyiv, Ukraine; and Julian E. Barnes and John Ismay from Washington.

Defense Secretary Pete Hegseth had the commercial messaging app Signal set up on a computer in his office at the Pentagon so that he could send and receive instant messages in a space where personal cellphones are not permitted, according to two people with knowledge of the matter.

Mr. Hegseth’s move facilitated easier communications in a building where cell service is poor and personal phones are not allowed in certain areas. It was first reported by the Washington Post.

The defense secretary has two computers in his office, one for personal use and one that is government-issued, according to one of the people with knowledge of the matter. Both spoke on condition of anonymity because of the sensitivity of the situation.

Mr. Hegseth had cables installed in early March so that he could connect a private computer to Signal, according to a second person with knowledge of the matter.

His confidential assistant and Col. Ricky Buria, his junior military aide, had the same Signal capability, the person said.

The latest revelation came after The New York Times reported that Mr. Hegseth had shared highly sensitive and detailed attack plans in a Signal chat group that included his wife, his brother and his personal lawyer hours before a mission was launched against Houthi targets in Yemen on March 15.

He had shared essentially the same information in a group chat with top national security officials, also shortly before the strikes. The fact of that conversation became public when The Atlantic reported that its editor, Jeffrey Goldberg, had been inadvertently included in the group chat.

Trump administration officials suggested there was no issue with Mr. Hegseth’s use of Signal in his office.

“The secretary of defense’s use of communications systems and channels is classified,” said Sean Parnell, the chief spokesman for the Pentagon. “However, we can confirm that the secretary has never used and does not currently use Signal on his government computer.”

Karoline Leavitt, the White House press secretary, called it “another nonstory,” noting that Signal is an app approved for government use.

The Pentagon’s acting inspector general announced earlier this month that he would review Mr. Hegseth’s Yemen strike disclosures on Signal.

Senator Roger Wicker, a Mississippi Republican who chairs the Armed Services Committee, and the committee’s senior Democrat, Senator Jack Reed of Rhode Island, requested the review. In a letter last month, the senators asked the inspector general to conduct an inquiry into whether Mr. Hegseth had shared sensitive or classified information in the national-security group chat.

The details about the strikes that Mr. Hegseth sent came from U.S. Central Command through a secure government system designed for transmitting classified information, according to an official and a person familiar with the conversations.

Besides the disclosures of the Signal chats, in the past month Mr. Hegseth has seen the dissolution of his inner circle of close advisers — military veterans who, like him, had little experience running large, complex organizations. Three members of the team he brought with him into the Pentagon were accused last week of leaking unauthorized information, and escorted from the building.

President Trump and White House officials have stood by Mr. Hegseth through both controversies related to Signal.

But Mr. Hegseth also irritated White House officials by booking himself for a Fox News interview on Tuesday morning, during which he accused fired advisers of making up stories about him.

White House officials have told him they want him to get the fractious situation with his staffing under control, according to a person with knowledge of the discussions.

The flashy online announcement called it “the most EXCLUSIVE INVITATION in the World,” a chance to have “an intimate private dinner” with President Trump at his members-only golf club in Virginia, followed by a tour of the White House.

A seat would be reserved for each of the top 220 investors in $TRUMP, a cryptocurrency that Mr. Trump launched on the eve of his inauguration.

In an astonishing escalation of the Trump family’s efforts to profit from crypto, a website promoting $TRUMP, the president’s so-called memecoin, announced on Wednesday that the coin’s largest buyers would be invited to meet him. The effort was, in effect, an offer of access to the White House in exchange for an investment in one of Mr. Trump’s crypto ventures.

“Have Dinner with President Trump and the $TRUMP Community!” the invitation said. “Let the President know how many $TRUMP coins YOU own!”

For months, Mr. Trump’s forays into crypto have created ethical conflicts with little precedent in presidential history. As he markets digital currencies to the public, Mr. Trump has also appointed regulators who are scaling back crypto enforcement and called for legislation that would boost the industry’s prospects in the United States.

As news of the dinner invitation spread on social media, the memecoin’s price surged more than 60 percent, suggesting that investors were rushing to accumulate enough coins to qualify for a dinner seat.

“This is really incredible,” said Corey Frayer, who oversaw crypto policy for the Securities and Exchange Commission during the Biden administration. “They are making the pay-to-play deal explicit.”

A business entity linked to Mr. Trump owns a large tranche of the coins, meaning the president personally profits every time the price increases, at least on paper. Mr. Trump and his business partners also collect fees when the coins are traded, a windfall that amounted to nearly $100 million in the weeks after the coin debuted in January.

Victoria Haneman, a law professor at Creighton University, said the offering raised concerns about the ways Mr. Trump and his businesses “may maneuver to profit off the presidency.”

Early this year, the S.E.C. issued official guidance saying memecoins, a type of cryptocurrency based on an online joke or celebrity mascot, will not be subject to oversight by the agency. Crypto skeptics criticized the policy as a risky move that could open the door to rampant fraud by memecoin promoters.

As president, Mr. Trump has broad immunity from laws governing conflicts of interest, a loophole he has pointed out in the past. Representatives for the White House did not immediately respond to requests for comment. Mr. Trump’s son Eric, who helps run the Trump Organization, a sponsor of the $TRUMP coin, declined to comment.

Once a cryptocurrency skeptic, Mr. Trump embraced digital currencies on the campaign trail last year, as crypto companies poured tens of millions of dollars into the 2024 election.

In the fall, Mr. Trump and his sons, Donald Jr., Eric and Barron, said they were starting a company, World Liberty Financial, that offered a digital currency called WLFI. So far, $550 million of those coins have been sold, according to the company.

Not long after, Mr. Trump’s social media firm, Trump Media & Technology Group, moved to offer crypto-related financial products to amateur investors and announced a partnership with Crypto.com, a digital trading platform.

But Mr. Trump’s memecoin venture has generated the most attention.

Just three days before the inauguration, Mr. Trump posted on Truth Social, his social media site, that he was selling the coin. Sales of $TRUMP immediately spiked, making the president-elect a crypto billionaire on paper.

Memecoins tend to rise and fall quickly, and $TRUMP’s price soon cratered. Traders who had accumulated the coin suffered more than $2 billion in cumulative losses.

The dinner announcement appeared calculated to ignite more interest in the coins.

When $TRUMP went on sale in January, a large stash of the coins were allocated to the project’s backers. But rules built into the offering prevented those insiders from selling any of the coins until last week, raising fears that they would try to offload their holdings and cause $TRUMP’s price to drop further.

Instead, the price gradually climbed in the days before the invitation was released and then surged as the announcement went live.

On the memecoin’s website, the $TRUMP promoters set up a leaderboard of the coin’s biggest investors — essentially an online game allowing buyers to track their place in the rankings. Dinner invitations would go to the “top 220 average $TRUMP owners” between April 23 and May 12, the website said. The top 25 buyers would win access to a reception with Mr. Trump before the dinner and a V.I.P. tour of the White House. (At the moment, the 25th-ranked investor on the chart owns about 4,000 coins, worth roughly $54,000.)

“The more $TRUMP you hold — and the longer you hold it — the higher Your Ranking will be,” the website said.

The dinner with Mr. Trump is scheduled to take place on May 22 at the Trump National Golf Club, the website said, calling it the “Most Exclusive Once in Lifetime Invitation.”

As Elon Musk sought to reassure Wall Street analysts on Tuesday that he would soon scale back his work with the federal government, the strain of his situation was audible in his voice.

The world’s richest man said that he would continue arguing that the Trump administration should lower tariffs it has imposed on countries across the world. But he acknowledged in a subdued voice that whether President Trump “will listen to my advice is up to him.”

He was not quite chastened, but it was a different Mr. Musk than a couple months ago, when the billionaire, at the peak of his power, brandished a chain saw onstage at a pro-Trump conference to dramatize his role as a government slasher.

Back then, Mr. Musk was inarguably a force in Washington, driving radical change across the government. To the president, he was a genius; to Democrats, he was Mr. Trump’s “unelected co-president”; to several cabinet secretaries, he was a menace; and to G.O.P. lawmakers, he was the source of anguished calls from constituents whose services and jobs were threatened by cuts from his Department of Government Efficiency.

As Mr. Musk moves to spend less time in Washington, it is unclear whether his audacious plan to overhaul the federal bureaucracy will have lasting power. The endeavor has already left an immense imprint on the government, and Mr. Musk has told associates that he believes he has put in place the structure to make DOGE a success. But he has still not come close to cutting the $1 trillion he vowed to find in waste, fraud and abuse.

Mr. Trump has constrained some of Mr. Musk’s influence over the past two months, telling cabinet secretaries that they were in charge of their own agencies. But the president also told the secretaries to work with Mr. Musk and DOGE to cut spending. At the same time, Mr. Musk has fought publicly and privately against the president’s steep tariffs that have threatened the manufacturing and profits of Tesla, his car company.

Mr. Musk has told friends that he has been frustrated by the encounters he has had with Mr. Trump’s trade advisers, according to a person briefed on the conversations who spoke on the condition of anonymity to describe private discussions. The billionaire has tried to work behind the scenes to persuade Mr. Trump to abandon his draconian protectionist posture, according to two people with knowledge of their conversations.

The White House did not respond to a request for comment, and a spokeswoman for Mr. Musk declined to comment. On Wednesday, Mr. Trump said the billionaire “was a tremendous help, both in the campaign and in what he’s done with DOGE.”

“He was always at this time going to ease out,” the president told reporters in the Oval Office.

Shaun Maguire, one of Mr. Musk’s closest friends and an adviser to DOGE officials, said that he was confident the endeavor would thrive without Mr. Musk’s full-time involvement. He compared DOGE to a Falcon 9 rocket — an initial thrust of energy powers the rocket even after it has separated from its engines.

“At this point, a rocket is only a couple hundred kilometers from Earth, but it has escaped its gravity well and can travel far into the solar system,” Mr. Maguire said. “DOGE has escaped D.C.’s gravity well.”

Mr. Maguire, who was involved in interviews for Pentagon appointments during the presidential transition, said he believed that “history will judge DOGE very favorably, well beyond what is appreciated today.”

Mr. Musk has placed DOGE allies across the federal government, seeking to dismantle some agencies, including the U.S. Agency for International Development and the Consumer Financial Protection Bureau.

The New York Times has identified more than 60 employees hired to work for Mr. Musk’s effort, although some have since left the federal government. Many have worked with the billionaire in the private sector, including at least 20 who have ties to Mr. Musk’s companies. DOGE is led by Steve Davis, Mr. Musk’s top adviser and enforcer.

DOGE staff members have overridden the objections of career civil servants at the Social Security Administration and the Internal Revenue Service to access closely held data about immigrants. Inside a Social Security database, Mr. Musk’s team put into place a system to list living immigrants they claimed were criminals as dead, in an effort to cut them off from financial services and to force them to leave the country.

All told, DOGE has tried to gain entry to more than 80 data systems across at least 10 federal agencies, The New York Times found. Those data sets include personal information about federal workers, detailed financial data about federal procurement and spending and intimate personal details about the American public.

Some of Mr. Trump’s advisers have watched anxiously as Mr. Musk has taken risky political swings at agencies that tens of millions of Americans rely on.

At the Social Security Administration, rushed policy changes have led to panicked beneficiaries overwhelming field offices. And a return-to-office policy and layoffs of probationary employees at the Department of Veterans Affairs have imperiled the agency’s mental health care program and threatened its ability to conduct medical research.

Mr. Musk came into the Trump administration claiming he would find governmental cost savings so large that they sounded impossible to budget experts.

In February, the group posted an online “wall of receipts” that detailed the savings from thousands of canceled grants, contracts and office leases. But that site included claims that confused “billion” with “million,” double- or triple-counted the same cancellations and even took credit for canceling programs that ended when George W. Bush was president.

Earlier this month, at a cabinet meeting, Mr. Musk said he had so far cut $150 billion from next year’s federal budget — far less than the $1 trillion he claimed he would extract.

DOGE has triggered sharp cuts to the federal work force and to the budgets of some agencies. But it is difficult to gauge exactly how much it has saved, because DOGE’s public claims have been riddled with errors and guesswork that inflated its success.

Mr. Musk’s slashing of the government has been politically costly, but he remains in good standing with the president, according to people familiar with Mr. Trump’s views.

While some of Mr. Trump’s close aides and advisers have argued with Mr. Musk, the president still praises him at nearly every opportunity, and still invites him to hang out at his clubs and to bring along his children.

Mr. Trump has told advisers that Mr. Musk put it all on the line for him. And he feels bad about what he calls left-wing “lunatics” attacking Tesla dealerships to protest Mr. Musk’s role in the Trump administration. Mr. Trump also respects the power of Mr. Musk’s social media platform, X, even as the president retains a commercial interest in Truth Social, his own platform.

In private, Mr. Trump has occasionally indicated to associates that it might be time for Mr. Musk to move on and spend more time with his companies. But the president is unlikely to ever pressure Mr. Musk to leave, or do anything deliberate to alienate him. He remains grateful for the hundreds of millions of dollars that Mr. Musk spent to elect him in 2024, and mindful of the additional $100 million that Mr. Musk has pledged to Mr. Trump’s political operation, the associates note.

Mr. Musk is now a financial cornerstone of the Republican Party, and will keep immense influence as long as he wants to stay involved in politics.

Still, Mr. Trump has recognized problems that Mr. Musk has caused, such as a plan for him to get briefed at the Pentagon on sensitive national security matters related to China — something even the president described privately as a conflict of interest and a meeting he was not told about in advance, according to people familiar with what took place. When Mr. Trump learned of that potential session from news reports, it was the first time people close to the president could remember him expressing displeasure with Mr. Musk.

Mr. Trump has also acknowledged to advisers that Mr. Musk has stumbled as a political force — most notably with his costly long-shot effort to flip a Wisconsin Supreme Court seat. Mr. Trump, a student of public opinion, has paid attention to the billionaire’s standing in opinion polls, watchful for any signs that Mr. Musk’s deep unpopularity might transfer.

But people close to Mr. Trump have also said that Mr. Musk has been helpful as a “heat shield,” absorbing unrelenting attacks that would otherwise be aimed at the president.

On Tuesday, Mr. Musk told analysts that he planned to dial back his government work to “a day or two per week” to turn his attention back to his companies. Administration officials with knowledge of Mr. Musk’s schedule said that they have already noticed he has reduced the amount of time he spends in Washington.

By dialing back the number of days he spends working for the White House, Mr. Musk can also potentially stretch out the 130 days he is allotted as a “special government employee.”

Zach Montague, Emily Badger, Wilson Andrews and Alexandra Berzon contributed reporting.