Mike Waltz, the U.S. ambassador to the United Nations, on Monday called on Russia to deescalate during an emergency meeting of the U.N.’s most powerful body over Russia’s recent incursion into Estonian airspace.

Waltz was appearing before the Security Council for the first time Monday, making his debut after his nomination faced months of delays and procedural hurdles before he was confirmed late last week.

“As we said, nine days ago, the United States stands by our NATO allies in the face of these airspace violations,” the former Republican congressman said.

“And I want to take this first opportunity to repeat and to emphasize the United States and our allies will defend every inch of NATO territory.”

Russia denied violating Estonian airspace. But tensions have been escalating recently, after Poland and Romania - both NATO members - said Russian drones breached their airspace.