Trump’s call with Putin was scheduled for today at 10 a.m. ET, with a subsequent conversation with Zelenskyy on Friday. Trump has previously expressed hope that the talks could result in a ceasefire, but his attempts at negotiations between Russia and Ukraine have failed to yield significant progress.

The U.S. decision to halt weapons shipments—including Patriot air-defense interceptors—shocked Kyiv and its NATO allies. Zelensky has said he is prepared to pay $15 billion for the systems.

The Pentagon, however, has framed the move as “preserving US forces’ readiness for Administration defense priorities,” according to Pentagon policy chief Elbridge Colby.

What world leaders will be watching for:

Trump’s direct engagement with both Putin and Zelensky signals a renewed attempt to position the U.S. as a central broker in peace negotiations.The abrupt pause in U.S. military aid has deepened rifts with European allies, who remain committed to supporting Ukraine and fear that Washington’s stance could undermine Western unity.With arms deliveries suspended, Ukraine is less able to defend itself against Russia’s near-daily bombing of civilians in Ukraine. 

Trump’s reluctance to maintain robust support for Ukraine is highly controversial. Critics in both the U.S. and Europe argue that withholding military aid at a critical juncture risks emboldening Russia and could force Ukraine into accepting unfavorable terms. The move has revived memories of Trump’s previous withholding of aid to Ukraine, which Trump parlayed into a deal for rare earth minerals.

For this story, Fortune used generative AI to help with an initial draft. An editor verified the accuracy of the information before publishing.