Special Envoy Steve Witkoff said Sunday that Russian President Vladimir Putin agreed to allow the United States and European nations to give Ukraine “Article 5-like protection” as a security guarantee to bring an end to the war.

“We were able to win the following concession: That the United States could offer Article Five-like protection, which is one of the real reasons why Ukraine wants to be in NATO,” Witkoff said Sunday on CNN.

It was “the first time we had ever heard the Russians agree to that,” he continued.

NATO’s Article 5 says that “if a NATO Ally is the victim of an armed attack, each and every other member of the Alliance will consider this act of violence as an armed attack against all members and will take the actions it deems necessary to assist the Ally attacked.”

European Commission President Ursula von der Leyen said Sunday that she welcomed the security guarantees for Ukraine, and that the “European Union … is ready to do its share,” according to the Associated Press.

Witkoff’s remarks come just days after President Donald Trump met in Alaska with Putin amid his country’s ongoing war with Ukraine. Trump and his administration hailed the talks as “productive,” but details of the meeting have so far been scant.

Trump, in the lead-up to his meeting with Putin, repeatedly stressed the need for an urgent, long-lasting ceasefire in the war.

The talks did not yield such an agreement, sparking concern among officials in Ukraine and European nations that Trump was moving away from the goal.

In the days since the talks, Trump, however, has said that the “best way” to end the war is “to go directly to a Peace Agreement.”

Witkoff said Sunday that Trump and Putin “covered almost all the other issues necessary for a peace deal” during their hours-long meeting, without providing additional details.

“We began to see some moderation in the way they’re thinking about getting to a final peace deal,” he said.

Secretary of State Marco Rubio also said Sunday that Russia will face “additional consequences” if Trump’s effort to end the war “doesn’t work out,” but warned against implementing additional sanctions.

“The minute you levy additional sanctions, strong additional sanctions, the talking stops,” he said on ABC News.

Rubio added that “we’re still a long ways off” from a peace agreement.

“We made progress in the sense that we identified potential areas of agreement, but there remain some big areas of disagreement,” he said. “We’re not at the precipice of a peace agreement, we’re not at the edge of one, but I do think progress was made towards one.”

Trump is set to meet with Ukrainian President Volodymyr Zelenskyy and European leaders on Monday.

Following Friday’s summit, Trump said a peace deal could be reached if Zelenskyy agreed to give up the Donbas region, the New York Times reported, citing senior European officials.

But Zelenskyy has been adamant that Kyiv will never recognize any of its sovereign territory as part of Russia, even regions Moscow has already annexed. The Ukrainian president has said doing so would violate the country’s Constitution. Ukraine has also said it wants any peace deal to include guarantees that Russia will never invade again.

— CNBC’s Terri Cullen contributed to this report