President Trump has ordered a pause on U.S. aid going to Ukraine in its war against Russia, a consequential move as he clashes with Ukrainian President Volodymyr Zelensky about the path to ending the conflict.

“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 said in a statement. “We are pausing and reviewing our aid to ensure that it is contributing to a solution.”

The pause applies to all military aid not already on the ground in Ukraine and will effect munitions, anti-tank weapons and other materials the U.S. has provided to Kyiv since Russia invaded roughly three years ago.

Trump took office with nearly $4 billion in drawdown authority available from previously approved congressional funding for Ukraine. That funding now appears poised to go unused.

The move is likely to increase the pressure on Zelensky to get back in Trump’s good graces or risk losing ground in the war. It is also likely to put the spotlight on European nations seeking to rally more support for Kyiv.

As of the end of fiscal 2024, Congress had approved nearly $183 billion in Ukraine aid, according to a federal government oversight office. The European Union has contributed roughly $145 billion in total assistance to Ukraine since the war began. 

Trump campaigned on a pledge to end the war in Ukraine. Since taking office, he has spoken with both Zelensky and Russian President Vladimir Putin.

Tensions have been heightened between Trump and Zelensky in recent weeks after the U.S. president called the Ukrainian leader a “dictator without elections” who had done a “terrible job.” Trump recently suggested Ukraine was to blame for the start of the war with Russia.

Zelensky responded at the time that Trump was living in a “disinformation space.”

The tensions appeared to culminate last Friday at a confrontational meeting in the Oval Office, after which Trump said the Ukrainian leader was not “ready for peace.”

Zelensky had arrived at the White House last week expecting to meet with Trump and sign off on a deal that would give the U.S. access to Ukraine’s critical mineral supply. Trump had touted the deal as a way for the U.S. to recoup some of the aid it had provided to Ukraine in its war against Russia, while boosting Ukraine’s economy in the long term.

But Trump called off peace talks, and the deal was left unsigned after the Oval Office blowup.

Trump said earlier Monday that the minerals deal was not dead, and that Zelensky could restart talks by showing appreciation for U.S. assistance.

Updated at 7:49 pm EST.