Russia on Tuesday dismissed accusations of any involvement in the poisoning of an ex-spy and his daughter as "nonsense," saying it will only cooperate with a British investigation if it receives samples of the nerve agent believed to have been used.
Police, meanwhile, said the investigation of who poisoned Sergei Skripal and his daughter, Yulia, will last many weeks and that they are not ready to identify any persons of interest in the inquiry. The father and daughter remain in critical condition in a Salisbury hospital.
British Prime Minister Theresa May said Russia's involvement is "highly likely," and she gave the country a deadline of midnight Tuesday to explain its actions in the case. She is reviewing a range of economic and diplomatic measures in retaliation for the assault with what she identified as the military-grade nerve agent Novichok.
US and European officials were quick to offer words of support for Britain, which will need the backing of its allies if any new sanctions are to have any impact.