British Prime Minister Theresa May says her government has concluded it is "highly likely" Russia is responsible for the poisoning of an ex-spy and his daughter.
May told British lawmakers on Monday that Sergei Skripal and his daughter, Yulia, were exposed to a nerve agent known as Novichok (Novice), a weapon developed in the Soviet Union in the end of the Cold War
May says the attack in a city in England fits a pattern of Russian aggression and that Russia's ambassador to the UK has been summoned to explain what happened.
She said: "We will not tolerate such a brazen attempt to murder innocent civilians on our soil."
Skripal and his daughter remain in critical condition more than a week after they were found unconscious in Salisbury on March 4.