Theresa May faces increasing pressure to take action against those responsible for the nerve agent attack on a former Russian spy and his daughter.
There is little doubt amongst ex-diplomats and former members of the intelligence services that the Moscow was involved in the attack, but the government has not yet pointed the finger at the Kremlin.
Sergei and Yulia Skripal remain in a critical but stable condition after the incident on 4 March, when the pair were found slumped over on a bench in Salisbury.
The 66-year old Russian-born Sergei Skripal was convicted in 2004 for sharing Russian secrets with MI6 over a number of years, but was released from prison in Russia in a so-called “spy swap” in 2010 and moved to the UK with his daughter Yulia.
The Kremlin has denied responsibility for the attack, but the use of a complex and rare nerve agent means that the perpetrator is most likely a nation with a technologically advanced military. The targeting of a former Russian spy in such a brazen act implies Kremlin involvement, but there is little conclusive evidence.
Russia also has a history of murdering former double-agents on UK soil. A public inquiry into the 2006 poisoning of Alexander Litvinenko with radioactive isotope polonium-210 concluded the murder was “probably” organised by Moscow’s FSB intelligence service and approved by Russian President Vladimir Putin. Russia still denies involvement in Litvinenko’s death, but has refused to cooperate with investigators and rejected extradition requests to bring the two main suspects back to the UK to face trial. One of the two men accused of the murder, former KGB agent Andrey Lugovoy, is now deputy of the Russian State Duma.
On Monday, the prime minister will chair a National Security Council meeting to discuss the latest intelligence with ministers and security chiefs.