March 16 (UPI) -- Russia said it will retaliate against the United States and Britain for claiming Moscow is responsible for the poisoning of an ex-spy and implementing sanctions.
British Foreign Secretary Boris Johnson said Friday it was "overwhelmingly likely" that it was Russian President Vladimir Putin's decision to have former Russian double agent Sergei Skripal attacked with a Soviet-era nerve agent.
Kremlin Spokesman Dmitry Peskov said blaming Putin for the attack was undiplomatic.
"We have said on different levels and occasions that Russia has nothing to do with this story," Peskov said. "Any reference or mentioning of our president is nothing else but shocking and unpardonable diplomatic misconduct,"
Russia has faced growing international criticism over their alleged role in the nerve agent attack on Skripal and his daughter, Yulia, in Salisbury. The Skripals remain in critical condition.
Germany, France and the United States joined Britain in blaming Moscow for the attack, with British Prime Minister Theresa May stating it was "highly likely" that Russia was responsible. In response, May expelled 23 Russian diplomats from Britain.
Meanwhile, the United States Treasury sanctioned five Russian entities and 19 citizens Thursday for their role in interfering with the 2016 U.S. presidential election -- slamming Moscow for its "reckless and irresponsible conduct."
In retaliation, Moscow announced plans to blacklist Americans and expel British diplomats, claiming they were ready to escalate a standoff with the West. The number of Americans on the sanctioned people list will be raised to match that U.S. tally.
Peskov said Friday that Britain should expect retaliatory measures "at any moment."
"Retaliatory measures will not be long in coming," Peskov said, adding that the Kremlin was "surprised" at the accusations that Russia was involved in the poisoning of former Russian double agent Sergei Skripal and his daughter.
Russia's Foreign Minister Sergei Lavrov, who previously said Russia "stopped paying attention" to British statements about the nerve agent attack, claimed that Britain's Secretary of State for Defense Gavin Williamson lacked education after Williamson said Russia should "go away and shut up."
"Theresa May's 'highly likely' is the main argument supporting the Russia blame game and his would be 'Russia should go away and shut up'," Lavrov said. "Maybe he lacks education, I don't know."
Russia said Friday it was launching its own investigation into the attempted murder of Yulia Skripal.
"An investigation will be conducted in accordance with the Russian legislation and international law," Russia's Investigative Committee spokeswoman Svetlana Petrenko said, adding Moscow would "engage highly qualified experts" and was ready to cooperate with British law enforcement agencies.