President Trump on Monday temporarily suspended the delivery of all U.S. military aid to Ukraine, senior administration and military officials said, just days after Mr. Trump and President Volodymyr Zelensky of Ukraine had an explosive confrontation at the White House.
The order affects more than $1 billion in arms and ammunition in the pipeline and on order. It resulted from a series of meetings at the White House on Monday between Mr. Trump and his senior national security aides, the officials said, speaking on the condition of anonymity to discuss internal deliberations.
The officials said the directive would be in effect until Mr. Trump determined that Ukraine had demonstrated a good-faith commitment to peace negotiations with Russia.
Mr. Trump’s decision dramatically escalates the breach between Washington and Kyiv, at a critical moment in the conflict. The most immediate beneficiary of the move is President Vladimir V. Putin of Russia. If the suspension is lengthy, he can use the time to press for further territorial gains. And he may well decide to hold back from any negotiations at all, figuring that any prolonged dispute between Mr. Trump and Mr. Zelensky will only strengthen his position, either on the battlefield or when cease-fire talks ever take place.
Mr. Trump’s move has few direct precedents in recent American history. While the United States has paused the transfer of specific weapons systems to allies and partners, such as President Joseph R. Biden Jr.’s decision to suspend deliveries of 2,000-pound bombs to Israel that he feared could be used against civilians in Gaza, a full cutoff is essentially an ultimatum. It forces Mr. Zelensky to agree to a cease-fire on terms Mr. Trump dictates, or condemns the country to larger battlefield losses.
The suspension also puts the United States in direct opposition to its major NATO allies. Most of the largest European nations, led by France, Britain and Germany, have pledged to step up aid to Ukraine in recent days, siding with Mr. Zelensky in his dispute with the Trump administration. But they simply do not have the stockpiles to make up the difference in the short term.