Moscow will retaliate against British targets in Ukraine or elsewhere if Kiev uses UK-provided missiles to strike Russian territory, the Foreign Ministry told London’s ambassador on Monday.

Ambassador Nigel Casey was summoned to the ministry following remarks by British Foreign Secretary David Cameron to Reuters that Ukraine has the right to use long-range missiles sent by the UK to strike deep inside Russia.

”Casey was warned that the response to Ukrainian strikes using British weapons on Russian territory could be any British military facilities and equipment on the territory of Ukraine and beyond,” the Russian Foreign Ministry said in a statement following the meeting.

The US and its allies had previously qualified their deliveries of long-range weapons to Kiev by saying they could only be used on territories that Ukraine claims as its own – Crimea, the People’s Republics of Donetsk and Lugansk, and Kherson and Zaporozhye Regions.

READ MORE: Western ambassadors summoned in Moscow

According to the Russian Foreign Ministry, Cameron’s statements to the contrary “de facto recognized his country as a party to the conflict.”

Russia understands Cameron’s comments as “evidence of a serious escalation and confirmation of London’s increasing involvement in military operations on the side of Kiev,” the ministry added.

Casey was urged to “think about the inevitable catastrophic consequences of such hostile steps from London and to immediately refute in the most decisive and unequivocal manner the bellicose provocative statements of the head of the Foreign Office.”

Earlier in the day, the Russian Defense Ministry announced an exercise to test the deployment of tactical nuclear weapons. President Vladimir Putin ordered the drills after “provocative statements and threats” by Western officials, the military said.

Moscow hopes the drills will “cool down the ‘hot heads’ in Western capitals and help them understand the possible catastrophic consequences of the strategic risks they generate,” as well as “keep them from both assisting the Kiev regime in its terrorist actions and being drawn into a direct armed confrontation with Russia,” the Foreign Ministry said in a follow-up statement.

French Ambassador Pierre Levy was also summoned to the Foreign Ministry. Moscow has not yet disclosed the details of the meeting.