EU foreign ministers and the head of NATO have strongly condemned the poisoning of a former Russian double agent in Britain, and offered London "solidarity" over the attack.
NATO Secretary-General Jens Stoltenberg said on March 19 that NATO allies had been "united in condemning this attack," which he called an "unacceptable breach of international norms and rules."
The comments echoed a statement earlier in the day from EU foreign ministers, which read that the bloc "takes extremely seriously the U.K. government's assessment that it is highly likely that the Russian Federation is responsible."
Sergei Skripal, 66, and his 33-year-old daughter, Yulia, remain in critical condition after they were found collapsed on a bench in the southern English city of Salisbury on March 4. Britain says they were exposed to a Soviet-designed military-grade nerve agent known as Novichok, and blames Moscow for the attack. Russia denies involvement.
The EU ministers said that the bloc "expresses its unqualified solidarity with the U.K. and its support, including for the U.K.'s efforts to bring those responsible for this crime to justice."
Stoltenberg said Russia's response to the poisoning "so far has demonstrated a clear disregard for international peace and security."
"We continue to call on Russia to provide complete disclosure of the Novichok program to the Organization for the Prohibition of Chemical Weapons (OPCW)," he added.
The NATO chief said the attack in Salisbury "comes at the background of a pattern of reckless behavior of Russia." He cited Russia's "illegal annexation of Crimea," its "continued efforts to destabilize eastern Ukraine," and its efforts to "interfere in our democratic political processes and undermine our democratic institutions."
"Russia will continue to seek to divide us," Stoltenberg. "But NATO allies stand united. And we stand in solidarity with the U.K."
U.K. Foreign Secretary Boris Johnson said on March 16 that it was "overwhelmingly likely" that Russian President Vladimir Putin made the decision to use the nerve agent on Skripal, an accusation the Kremlin said was "unforgivable."
On March 18, in his first public remarks on the poisoning, Putin flatly rejected Britain's accusations. Addressing reporters as he was headed for a landslide reelection, Putin said Russia "has no such" weapon.
U.K. Prime Minister Theresa May on March 19 rejected Putin's denial, telling Sky News, "I am clear that what we have seen shows that there is no other conclusion but the Russia state is culpable for what happened” in Salisbury.
Meanwhile, French President Emmanuel called on Russia to “shed light on the responsibilities for the unacceptable attack” in Salisbury in a phone call with Putin.
He also urged Moscow to “firmly regain control of any programs that have not been declared” to the OPCW, said a statement from the French president's office.
OPCW inspectors on March 19 began running independent tests on samples taken from Salisbury to verify the British analysis, Reuters reported, citing an OPCW source.
"The team from The Hague will meet with officials from the Defense Science and Technology Laboratory and the police to discuss the process for collecting samples, including environmental ones," Britain's Foreign Office said.
Britain has identified the nerve agent as Novichok -- a Soviet-designed military-grade nerve agent.
May's spokesman said Britain's National Security Council will meet on March 20 to discuss potential next steps against Russia.
But the Kremlin on March 19 reiterated that Britain must prove Russia's involvement in the poisoning of Skripal and his daughter or apologize.
"Sooner or later these unsubstantiated allegations will have to be answered for: either backed up with the appropriate evidence or apologized for," presidential spokesman Dmitry Peskov said.
Speaking in Brussels ahead of the EU foreign ministers meeting, Johnson said Moscow's denials over its involvement in the poisoning of the former Russian double agent in Britain were becoming "increasingly absurd."
"This is a classic Russian strategy of trying to conceal the needle of truth in a haystack of lies and obfuscation, they're not fooling anybody anymore," Johnson said, as he arrived in Brussels.
Johnson added that "there is scarcely a country around the table here in Brussels that has not been affected in recent years by some kind of malign or disruptive Russian behavior."
The poisoning prompted Britain to announce the expulsion of 23 Russian diplomats, with Moscow saying it would reciprocate by expelling the same number of British diplomats.
In a joint statement with Britain on March 15, the leaders of the United States, France, and Germany condemned the attack as "an assault on U.K. sovereignty."
"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.
Skripal is a former Russian military intelligence officer who was convicted of treason in 2006 for passing the identities of Russian intelligence agents to Britain's Secret Intelligence Service, or MI6. He was one of four Russian prisoners released in 2010 in exchange for 10 Russian sleeper agents uncovered in the United States.