The leaders of France, Germany, the US and the UK jointly demanded "complete disclosure" from Russia on the Novichok nerve agent used in the attack on former spy Sergei Skripal, saying there is "no plausible alternative" to Moscow's involvement.

"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," they said in a statement on Thursday. The attack constituted "an assault on UK sovereignty" that threatened "the security of us all."

Read more: Nerve agent attack a 'serious violation' of international agreements, says Germany's Von der Leyen

Unprecedented attack

On March 4, Skripal, a 66-year-old former military intelligence agent who betrayed several Russian agents to British intelligence, and his 33-year-old daughter Yulia, were targeted in the attack. Both remain unconscious in intensive care.

Nick Bailey, the first police officer on the scene, is also in stable but critical condition. Up to 21 other people were treated for exposure, according to police.

The joint statement called on Moscow to provide information on its nerve poison to the Organization for the Prohibition of Chemical Weapons (OPCW), especially after Russia claimed it destroyed all of its chemical weapons stockpiles last year. In an article for Germany's Frankfurter Allgemeine newspaper, British Foreign Minister Boris Johnson said London is working to give the OPCW "the opportunity to confirm our analysis independently."

The UK deployed military personnel to the streets of Salisbury to remove potentially contaminated vehicles

'Reckless behavior'

NATO Secretary General Jens Stoltenberg on Thursday said he backed a "proportionate" response from British authorities, adding that the incident must have "consequences."

"The attack in Salisbury has taken place against a backdrop of reckless behavior by Russia over many years," said Stoltenberg. "I fully support that there is a need for a response because it has to have consequences when we see actions like we have seen in Salisbury."

Read more: Spy assassinations: The top 5 deadly poisons

The NATO chief noted that the UK had not invoked Article 5, the transatlantic alliance's collective defense clause. It has only been invoked once in the alliance's history, by the US in the wake of the September 11, 2001 attacks.

Stoltenberg is expected to meet with British Foreign Minister Boris Johnson to further discuss the attack on British soil.

A history of political poisonings Alexei Navalny Russian opposition leader Alexei Navalny was rushed to hospital in Siberia after being taken ill on a flight to Moscow. His aides allege he was poisoned in revenge for his campaigns against corruption. The 44-year-old ex-lawyer apparently only drank black tea before taking off from Omsk airport, which his team think was laced with a toxin that put him in a coma.

A history of political poisonings Pyotr Verzilov In 2018, Russian-Canadian activist Pyotr Verzilov was reported to be in a critical condition after allegedly being poisoned in Moscow. It happened shortly after he gave a TV interview criticizing Russia's legal system. Verzilov, the unofficial spokesman for the rock group Pussy Riot, was transferred to a hospital in Berlin where doctors said it was "highly probable" that he had been poisoned.

A history of political poisonings Sergei Skripal Sergei Skripal, a 66-year-old former Russian spy, was found unconscious on a bench outside a shopping center in the British city of Salisbury after he was exposed to what was later revealed to be the nerve agent Novichok. Russian President Vladimir Putin’s spokesman Dmitry Peskov called the situation "tragic" but said, "We don't have information about what could be the cause" of the incident.

A history of political poisonings Kim Jong Nam The estranged half-brother of Kim Jong Un was killed on February 13, 2018 at Kuala Lumpur airport after two women allegedly smeared the chemical nerve agent VX on his face. In February, a Malaysian court heard that Kim Jong Nam had been carrying a dozen vials of antidote for the deadly nerve agent VX in his backpack at the time of the poisoning.

A history of political poisonings Alexander Litvinenko Former Russian spy Litvinenko had worked for the Federal Security Service (FSB) before he defected to Britain, where he became a journalist and wrote two books of accusations against the FSB and Putin. He became ill after meeting with two former KGB officers and died on November 23, 2006. A government inquiry found he was killed by radioactive polonium-210 which it alleged the men put in his tea.

A history of political poisonings Viktor Kalashnikov In November 2010, doctors at Berlin's Charité hospital discovered high levels of mercury had been found in a Russian dissident couple working in Berlin. Kalashnikov, a freelance journalist and former KGB colonel, had 3.7 micrograms of mercury per litre of blood, while his wife had 56 micrograms. A safe level is 1-3 micrograms. Viktor reportedly told German magazine Focus that "Moscow poisoned us."

A history of political poisonings Viktor Yushchenko Ukrainian opposition leader Yushchenko became sick in September 2004 and was diagnosed with acute pancreatis caused by a viral infection and chemical substances. The illness resulted in facial disfigurement, with pockmarks, bloating and jaundice. Doctors said the changes to his face were from chloracne, which is a result of dioxin poisoning. Yushchenko claimed government agents poisoned him.

A history of political poisonings Khaled Meshaal On September 25, 1997, Israel's intelligence agency attempted to assassinate Hamas leader Meshaal, under orders from Prime Minister Benjamin Netanyahu. Two agents sprayed a poisonous substance into Meshaal's ear as he walked into the Hamas offices in Amman, Jordan. The assassination attempt was unsuccessful and not long afterward the two Israeli agents were captured.

A history of political poisonings Georgi Markov In 1978, Bulgarian dissident Markov was waiting at a bus stop after a shift at the BBC when he felt a sharp jab in his thigh. He turned to see a man picking up an umbrella. A small bump appeared where he felt the jab and four days later he died. An autopsy found he'd been killed by a small pellet containing a 0.2-milligram dose of ricin. Many believe the poisoned dart was fired from the umbrella.

A history of political poisonings Grigori Rasputin On December 30, 1916, mystic and spiritual healer Rasputin arrived at Yusupov Palace in St Petersburg at the invitation Prince Felix Yusupov. There, Prince Yusupov offered Rasputin cakes laced with potassium cyanide but he just kept eating them. Yusupov then gave him wine in a cyanide-laced wine glasses, but still Rasputin continued to drink. With the poison failing, Rasputin was shot and killed. Author: Louisa Wright, Nik Martin



Russia responds

The UK on Wednesday announced a range of measures against Russia, including expelling 23 diplomats.

Moscow said it would retaliate soon. British actions "go way beyond the framework of basic decency," Russian Foreign Minister Sergey Lavrov said Thursday.

Kremlin spokesman Dmitry Peskov accused the UK of taking a position that is "absolutely irresponsible," saying "these are all signs of a provocation against our country."

Read more: Bemusement in Salisbury as Russian ex-spy drama unfolds

'Warlike' actions

However, Tom Tugendhat, a British MP and chairman of the foreign affairs committee in the House of Commons, told DW that Russia's actions were "warlike."

"Had [this chemical] been opened on the London Underground, for example, it would have killed hundreds of people. And to use it next to a children's playground, where, had the children been there, it would have killed 30 or 40 children," said Tugendhat.

"This is a completely unacceptable, warlike act by a violent, deranged regime that is weakening and lashing out. This is a corrupt dictatorship that has to stop."

ls,dj/kms (Reuters, AFP, dpa)

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