WASHINGTON () President Donald Trump on Thursday urged Russian President Vladimir Putin to “STOP!” after a deadly barrage of attacks on Kyiv, Ukraine’s capital.

“I am not happy with the Russian strikes on KYIV. Not necessary, and very bad timing. Vladimir, STOP! 5000 soldiers a week are dying,” Trump said in a post on his Truth Social platform. “Lets get the Peace Deal DONE!”

Russia struck Kyiv with an hours-long barrage of missiles and drones. At least 12 people were killed and 90 were injured in the deadliest assault on the city since last July.

Trump’s frustration is growing as a U.S.-led effort to get a peace agreement between Ukraine and Russia has not made progress.

Trump lashed out at Ukrainian President Volodymyr Zelenskyy on Wednesday and accused him of prolonging the “killing field” by refusing to surrender the Russia-occupied Crimea Peninsula as part of a possible deal. Russia illegally annexed that area from Ukraine in 2014.

Zelenskyy has repeated many times during the war that began when Russia invaded in February 2022 that recognizing occupied territory as Russia’s is a red line for Ukraine. Zelenskyy noted Thursday that Ukraine had agreed to a U.S. ceasefire proposal 44 days ago as a first step to a negotiated peace, but that Moscow’s attacks had continued.

Trump’s criticism of Putin is notable because Trump has repeatedly said Russia, the aggressor in the conflict, is more willing than Ukraine to get a deal done.

Meanwhile, NATO Secretary General Mark Rutte arrived Thursday morning for a day of meetings as the White House has signaled it’s lost patience with peace talks between Ukraine and Russia and is prepared to step away from the table.

At the Pentagon, Rutte met with Defense Secretary Pete Hegseth and new Chairman of the Joint Chiefs Gen. Dan Caine, and he’s scheduled to meet with Secretary of State Marco Rubio and National Security Advisor Mike Waltz later in the day.

The Associated Press contributed to this report.