Russia on Monday threatened to strike British military facilities and said it would hold drills simulating the use of battlefield nuclear weapons amid sharply rising tensions over comments by senior Western officials about possibly deeper involvement in the war in Ukraine.

After summoning the British ambassador to the Foreign Ministry, Moscow warned that Ukrainian strikes on Russian territory with U.K.-supplied weapons could bring retaliatory strikes against British military facilities and equipment on Ukrainian soil or elsewhere.

The drills are a response to “provocative statements and threats of certain Western officials regarding the Russian Federation,” the Defense Ministry said in a statement.

It was the first time Russia has publicly announced drills involving tactical nuclear weapons, although its strategic nuclear forces regularly hold exercises. Tactical nuclear weapons include air bombs, warheads for short-range missiles and artillery munitions and are meant for use on a battlefield. They are less powerful than the strategic weapons — massive warheads that arm intercontinental ballistic missiles and are intended to obliterate entire cities.

French President Emmanuel Macron repeated last week that he doesn’t exclude sending troops to Ukraine, and U.K. Foreign Secretary David Cameron said Kyiv’s forces will be able to use British long-range weapons to strike targets inside Russia. Some other NATO countries providing weapons to Kyiv have balked at that possibility.

Russia’s Foreign Ministry summoned both the French and British ambassadors. It urged the British ambassador “to think about the inevitable catastrophic consequences of such hostile steps from London."

It wasn’t the first time Europe’s military support for Ukraine has prompted nuclear saber-rattling. In March 2023, after the U.K.’s decision to provide Ukraine with armor-piercing shells containing depleted uranium, Putin said he intends to deploy tactical nuclear weapons on the territory of Ukraine neighbor Belarus.