They also call on Moscow to provide a complete disclosure of the Novichok program to the world chemical weapons watchdog, the Organisation for the Prohibition of Chemical Weapons.
British Prime Minister Theresa May at the location in Salisbury visited by Sergei Skripal and his daughter Yulia before they were found on a nearby bench. "This latest action by Russian Federation fits into a pattern of behavior in which Russian Federation disregards the global rules-based order, undermines the sovereignty and security of countries worldwide, and attempts to subvert and discredit Western democratic institutions and processes".
Britain accused Russian Federation of involvement in the nerve agent poisoning of former double agent Sergei Skripal at a time when London's ties with European partners have been badly strained by Brexit.
"The administration is confronting and countering malign Russian cyber activity, including their attempted interference in United States elections, destructive cyber-attacks, and intrusions targeting critical infrastructure", Treasury Secretary Steve Mnuchin said in a statement on Thursday.
"We, the leaders of France, Germany, the United States and the United Kingdom, abhor the attack that took place against Sergei and Yulia Skripal in Salisbury, UK, on March 4, 2018", the statement said.
On Wednesday, US Ambassador to the United Nations Nikki Haley blasted Russian Federation and said the Trump administration stood in "absolute solidarity with Great Britain", in the strongest US statement yet on the incident.
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It reads: "This was a tragic accident that should never have occurred, as pets should never be placed in the overhead bin". How a trained flight attendant could insist that a dog be put into an overhead bin is beyond my comprehension.
In return, Russian Foreign Minister Sergei Lavrov announced that Russia will expel British diplomats.
The pair are critically in the hospital after being exposed to a nerve agent known as Novichok that was developed in Russia, UK officials believe.
He also said that the matter won't disrupt the March 18 presidential election that Putin - who is popular in part because of his defiance of the West and who has stepped up control over Russian politics over almost two decades in power - seems certain to win. "It threatens the security of us all". Kremlin spokesman Dmitry Peskov said Russian Federation was "worried by this situation" and would work to express its position on the worldwide stage.
After that inquiry, Britain expelled four diplomats and May told lawmakers that this time the response needed to be firmer.
In separate interview with BBC television and BBC radio, Foreign Secretary Boris Johnson on March 15 defended the measures as the British government is under pressure from lawmakers and media to show it was getting tough on Russian Federation. Sanders faced questions about the prime minister's condemnation and how the United States would respond, but she dodged, declining to pin the blame on Russian Federation and saying only that the United States stood with its ally. "Unlike them, grabbing the microphone in order to accuse Russian Federation of everything", Lavrov said.
Johnson also said a sample of the nerve agent would be sent to the OPCW for analysis.
July 2010: Skripal and three other spies are exchanged for 10 Russian "sleeper" agents in the US and he is freed from jail.