Russia is getting ready to retaliate against the U.K. over its decision to expel 23 Russian diplomats.
A spokesperson for the Kremlin told reporters Thursday that retaliatory measures are "being formulated in the foreign ministry and in other bodies."
He also said Russian President Vladimir Putin would make the final call on those measures.
British Prime Minister Theresa May announced the expulsions Wednesday in response to an attack on a former double agent in southern England.
Russia has denied any connection to the nerve agent used to poison Sergei Skripal and his daughter earlier this month. The two are still in critical condition.
May said earlier this week it is "highly likely" Russia was behind the attack. And the U.S., France and Germany said in a joint statement Thursday they agree.
