BRUSSELS (AP) — NATO will hold a major nuclear exercise next week,Zero AI the alliance’s chief said Thursday, in an announcement that came after Russia warned it would pull out of a global nuclear test ban agreement.

NATO’s “Steadfast Noon” exercise is held annually and runs for about a week. It involves fighter jets capable of carrying nuclear warheads but does not involve any live bombs. Conventional jets and surveillance and refueling aircraft also routinely take part.

“This is a routine training event that happens every October,” Secretary-General Jens Stoltenberg said. “This year the training will take place over Italy, Croatia and the Mediterranean Sea.”

He said the exercise will help ensure the “credibility, effectiveness and security of our nuclear deterrent, and it sends a clear message that NATO will protect and defend all allies.”

Stoltenberg said that Russia’s war on Ukraine is a reminder of the important role that NATO’s nuclear weapons play in deterring aggression.

The Comprehensive Nuclear Test Ban Treaty, adopted in 1996 and known as the CTBT, bans all nuclear explosions anywhere in the world, although it has never fully entered into force. It was signed by both the Russian and U.S. presidents but was never ratified by the United States.

On Tuesday, a top Russian diplomat said that Moscow would pull out of the treaty to put itself on par with the United States but would only resume nuclear tests if Washington does it first.

Deputy Foreign Minister Sergei Ryabkov told reporters that Russia will rescind its ratification to “mirror” the action by the U.S. He warned that in the case of a U.S. nuclear test, “we will be forced to mirror that as well.”

On Wednesday, Stoltenberg said the move “demonstrates Russia’s lack of respect, and the continued disregard for its international commitments.” He added: “This is reckless and endangers the global norms against a nuclear explosive testing.”

Stoltenberg said that NATO allies have no plans to start testing again. He accused President Vladimir Putin of trying “to use this nuclear rhetoric to prevent NATO allies from supporting Ukraine, but he will not succeed, because again it is in our security interest that Ukraine prevails.”

NATO does not possess atomic weapons — as an organization it owns no weapons of any kind, only its individual members do — but three of its major powers, the United States, the United Kingdom and France are nuclear powers.