Rep. Michael McCaulof Texas, one of the GOP’s most prominent foreign affairs hawks, announced he’d retire on Sunday while warning that, with Russia’s escalation of its invasion of Ukraine, “we got to be very careful not to be on the precipice of a World War III.”

McCaul made his statements to ABC News as he discussed last week’s incursion into Polish airspace of Russian drones, which led to NATO scrambling jets to intercept the vehicles. Russia said the intrusion was an error, but Poland and other European countries contended it was intentional. President Donald Trump said it “could have been a mistake.”

McCaul said the move was cause for alarm. “We’ve never seen anything like this in recent times,” the congressman said. “And so, what I’m concerned about is that the escalation here and the temperature rising, we got to be very careful not to be on the precipice of a World War III.”

McCaul has long pushed Trump to take a tougher stance on Russia and its invasion of Ukraine and he said he thinks the president is “waking up” that Russian President Vladimir Putin “is not negotiating in good faith.”

Trump has repeatedly praised Putin over the years and moved to cut off military aid to Ukraine, though he’s reversed course and supported a new increase. He invited Putin to Alaska for discussions last month about a cease-fire in Ukraine but the Russian president has yet to commit to one.

“I think he’s manipulating the president as a KGB officer would,” McCaul said of Putin, who used to work for the Russian intelligence service. “The more Putin irritates the president, I think the better we are in terms of defending NATO and Ukraine.”

A former anti-terrorism prosecutor and past chairman of the House Homeland Security and Foreign Affairs committee, McCaul, 63, is part of an older generation of foreign policy hawks who’ve tried to counter a younger crop of Republicans who are more skeptical about U.S. intervention elsewhere in the world.

McCaul becomes one of at least 10 House members leaving the chamber without seeking higher office, a tally that includes fellow GOP hawk Rep. Don Bacon of Nebraska, who’s been increasingly critical of Trump’s response to Putin.

McCaul said he would finish his term but that “I’m looking for a new challenge in the same space that would be national security, foreign policy, but just in a different realm.”