Former spy Sergei Skripal and his daughter were poisoned by a military-grade nerve agent of a type developed by Russia, Theresa May has told MPs. The PM said it was “highly likely” Russia was responsible for the Salisbury attack.
The Foreign Office summoned Russia's ambassador to provide an explanation. Mrs. May said if there is no credible response by the end of Tuesday, the UK would conclude there has been an unlawful use of force by Moscow.
The chemical used in the attack, the PM said, has been identified as one of a group of nerve agents known as Novichok.
Mrs. May said: Either this was a direct action by the Russian state against our country, or the Russian government lost control of its potentially catastrophically damaging nerve agent and allowed it to get into the hands of others.
She said Foreign Secretary Boris Johnson had told the ambassador Moscow must provide full and complete disclosure of the Novichok program to international body the Organization for the Prohibition of Chemical Weapons.
Mrs. May said the UK must stand ready to take much more extensive measures, and these would be set out in the Commons on Wednesday should there be no adequate explanation from Russia.
Retired military intelligence officer Mr Skripal, 66, and his daughter, Yulia, 33, were found slumped on a bench in Salisbury city centre on Sunday 4 March. They remain in a critical but stable condition in hospital. Detective Sgt Nick Bailey, who fell ill attending the pair, remains seriously ill, but has been talking to his family.
Mr Skripal was convicted by the Russian government of passing secrets to MI6 in 2004, but given refuge in the UK in 2010 as part of a spy swap.
Home Secretary Amber Rudd will chair a meeting of the government emergency committee Cobra on Tuesday to discuss the latest developments in the case.
Addressing the Commons following a meeting of the government's National Security Council, Mrs. May said: This attempted murder using a weapons-grade nerve agent in a British town was not just a crime against the Skripals.
It was an indiscriminate and reckless act against the United Kingdom, putting the lives of innocent civilians at risk.
Mrs. May told MPs the positive identification of this chemical agent was made by experts at the UK's Porton Down laboratory. She said Russia has previously produced the agent and would still be capable of doing so.
The decision to point the finger at Moscow was also based on Russia's record of conducting state-sponsored assassinations and our assessment that Russia views some defectors as legitimate targets for assassinations, the PM added.
Nato Secretary General Jens Stoltenberg said the use of any nerve agent was horrendous and completely unacceptable and officials were in touch with the UK.
Russian Foreign Ministry spokeswoman Maria Zakharova said Mrs May's statement was a circus show in the British parliament.
The conclusion is obvious - it's another information and political campaign based on provocation, she said.
Earlier, asked whether Russia was to blame, President Vladimir Putin told the BBC: Get to the bottom of things there, then we'll discuss this.
The question now is what action Mrs. May will be prepared to take on Wednesday once Russia has responded, or perhaps failed to respond.
The key will be the scale of the international co-operation she can secure. For it is one thing to crack down on wealthy Russians in London, but it is another to secure united international action against Moscow.
This is a tougher ask, particularly when President Trump has yet to comment on the Salisbury attack and many European partners are looking to soften existing sanctions against Russia.
Mrs May is promising extensive measures” - the question will be whether they will be enough to make the Kremlin think twice.