UK National Security Adviser Mark Sedwill has claimed that agents from Russian intelligence agencies spied on ex-spy Skripal and his daughter for at least the past five years.
The adviser made the allegations in a letter to NATO Secretary General Jens Stoltenberg on Friday, without providing any evidence to support his claims.
Additionally, Mr. Sedwill claimed that Russia established a program over a decade ago to train agents to use chemical warfare agents, according to Sky News.
UK Prime Minister Theresa May quickly blamed the attack on Russia and expelled 23 diplomatic staff from the country. Moscow reacted with a retaliatory tit-for-tat package of diplomatic sanctions against Britain.
Over a dozen UK allies in North America and Europe expelled Russian diplomats in solidarity with the British government, and these expulsions were also met with retaliatory measures from the Kremlin.
The Russian Embassy in London presented a report earlier today saying that "any modern chemical laboratory is capable of synthesizing" the chemical agent reportedly used in the incident in Salisbury.