Trump refused to rule out a pause when asked by reporters.
US President Donald Trump has suspended military aid to Ukraine, a White House official said, sharply stepping up pressure on Kiev to agree to peace talks with Russia.
The move comes just days after a stunning public clash between Ukrainian President Volodymyr Zelensky and Trump.
Trump refused to rule out a pause when asked by reporters.
"The president has made it clear he is focused on peace. We need our partners to commit to that goal as well," a White House official told AFP, speaking on condition of anonymity.
"We are pausing and reviewing our assistance to ensure it contributes to a solution," the official added.
Trump also warned that he "will not tolerate" Zelensky's defiant stance for much longer, and said the Ukrainian leader should be "more grateful" for US support.
Speaking at the White House, Trump said Zelensky "won't hold out very long" without a ceasefire agreement with Moscow.
The pause is effective immediately and affects hundreds of millions of dollars worth of weapons that are in the process of being sent to Ukraine, the New York Times reported.
Zelensky, for his part, said he was seeking to end the war "as soon as possible."
The comments were made after the Ukrainian president accused Russia, which invaded Ukraine in 2014 and significantly expanded the conflict in 2022, of not being serious about peace.
Zelensky insisted that strict security guarantees were the only way to end the conflict.
But Trump's stance has shaken U.S. support for Ukraine and Washington's allies more broadly and fueled fears that the United States is pivoting toward Russia.
"It was the lack of security guarantees for Ukraine 11 years ago that allowed Russia to start with the occupation of Crimea and the war in the Donbass, and then the lack of security guarantees allowed Russia to start a full-scale invasion," Zelensky said.
Russia dismissed his comments, accusing him of not wanting peace - a repeat of US criticism.
Trump has previously called Zelensky, president since 2019, a "dictator" for not holding elections even though martial law rules out any vote because of the war.
Zelensky has rejected calls to resign, repeating his pledge to do so only if Ukraine gains NATO membership, which Russia - and now the US under Trump - opposes.
Germany's likely next chancellor, Friedrich Merz, said the surprise clash was a "deliberate escalation" by Trump. | BGNES