U.S., U.K., France and Germany issue statement blaming Russia for poisoning of ex-spy

The United States, France and Germany joined Britain on Thursday in condemning Russia for the nerve-agent poisoning of a former spy, calling it an "assault on U.K. sovereignty," as the Kremlin vowed to expel British diplomats soon in response to London's moves against Moscow.

Britain says blame for the poisoning of Sergei Skripal and his daughter in the English city of Salisbury lies with the Russian state. Prime Minister Theresa May responded by expelling 23 Russian diplomats, severing high-level contacts with Moscow and vowing to take both open and covert actions against Russian dirty money and "hostile state activity."

Russian Foreign Minister Sergei Lavrov said Moscow would "certainly" expel some British diplomats soon in retaliation.

In a rare joint statement, May and U.S. President Donald Trump, French President Emmanuel Macron and German Chancellor Angela Merkel said "there is no plausible alternative explanation" to Russian responsibility for the poisoning.

"This use of a military-grade nerve agent, of a type developed by Russia, constitutes the first offensive use of a nerve agent in Europe since the Second World War," the leaders said, calling it "an assault on U.K. sovereignty" and "a breach of international law."

Trump, who has often been reluctant to criticize Russian President Vladimir Putin, said it "certainly looks like the Russians were behind it."

Trump spoke to reporters at the White House after his administration announced new sanctions on Russian entities for alleged meddling in the 2016 U.S. presidential election.

In a statement also issued on Thursday, Prime Minister Justin Trudeau reiterated his support for the U.K.

"Canada is unwavering in its commitment to the United Kingdom," he said.

"The United Kingdom can count on Canada's full support in efforts to hold Russia to account for this unacceptable and unlawful behaviour.

"We will work closely with the United Kingdom, as well as with our international partners and through international institutions, to address this very serious situation.‎"

Novichok class of nerve agents

The four-nation statement is the fruit of British efforts to enlist international support as it tries to hold Russia accountable for the March 4 attack that left the former Russian agent and his daughter in critical condition and a British police officer seriously ill.

Russia denies being the source of the nerve agent that poisoned the Skripals and has demanded Britain share samples collected by investigators. Britain says the poison used was Novichok, a class of nerve agent developed by the Soviet Union toward the end of the Cold War as a part of a secret chemical weapons program.

Russian Deputy Foreign Minister Sergei Ryabkov said Russia had halted all chemical weapons research after joining the Chemical Weapons Convention that came into force in 1997, and completed the destruction of its stockpiles last year.

The poisoning has sparked a war of words from senior politicians in London and Moscow, increasing tensions between the two countries.​

The British prime minister visited Salisbury on Thursday, viewing the site where the Skripals were found critically ill on a park bench. It is now a scene of police tape and forensic tents, one of several scattered across the quiet cathedral city as police, supported by troops with chemical-weapons training, try to discover how and where the poison was administered.

British measures against Russia included scrapping an invitation for Lavrov to visit and withdrawing U.K. ministers and royals from the soccer World Cup this summer in Russia — although the England team will still compete.

May said Britain would also clamp down on murky Russian money and strengthen the government's ability to impose sanctions on those who abuse human rights, although she gave few details.

Britain is also trying to build a unified Western response, saying the attack in Salisbury is just the latest example of Russia's disregard for the rule of law.

'Pattern' of 'irresponsible behaviour'

In their statement, Trump, Macron, Merkel and May cited "a pattern of earlier irresponsible Russian behaviour" and called on Russia to disclose details of its Novichok program to the Organisation for the Prohibition of Chemical Weapons.

"We call on Russia to live up to its responsibilities as a member of the UN Security Council to uphold international peace and security," they said.

The leaders did not say what, if any, actions they would take if Russia does not comply.

At the White House, Trump said the nerve-agent attack is "something that should never ever happen."

"We're taking it very seriously as I think are many others," he said.