WASHINGTON, United States (AFP) — US President Donald Trump suspended military aid to Ukraine on Monday, a White House official said, sharply escalating pressure on Kyiv to agree to peace negotiations with Russia.

The move comes just days after a stunning public clash between Ukrainian President Volodymyr Zelensky and Trump, who is seeking a rapid end to the war.

Trump earlier on Monday had declined to rule out a pause when quizzed by reporters, but any disruption in the flow of US arms to the front line would rapidly weaken Ukraine’s chance of beating back Russia’s invasion.

“The President has been clear that he is focused on peace. We need our partners to be committed to that goal as well,” a White House official told Agence France-Presse, speaking on condition of anonymity.

“We are pausing and reviewing our aid to ensure that it is contributing to a solution,” the official added.

Congressional Democrats immediately condemned the pause as dangerous and illegal.

“My Republican colleagues who have called Putin a war criminal and promised their continued support to Ukraine must join me in demanding President Trump immediately lift this disastrous and unlawful freeze,” said Gregory Meeks, top Democrat on the House Foreign Affairs Committee.

Trump also warned he would “not put up” much longer with Zelensky’s defiance, and said Ukraine’s leader should be “more appreciative” of US support.

Speaking at the White House, Trump said Zelensky “won’t be around very long” without a ceasefire deal with Moscow.

The pause has gone into effect immediately and impacts hundreds of millions of dollars of weaponry in the process of being sent to Ukraine, The New York Times reported.

Ukrainian media said the move played into the Kremlin’s hands.

“We live in a reality where the United States has become an ally of North Korea, Russia and Iran and it is helping them carry out aggression against a European country,” media commentator Denys Kazansky said on social media.

“All those who demand peace from us ignore that the price of our peace will be higher than the price of our war,” said Pavlo Kazarin, a journalist and commentator who joined the military.

Iryna Gerashchenko, an opposition lawmaker in the Ukrainian parliament said Kyiv needed to repair ties with Washington.