On 4 March 2018, former double agent Sergei Skripal was poisoned with a Novichok nerve agent in Salisbury. Ten days later, the British government formally accused the Russian state of attempted murder, a charge which Russia denied. After the UK expelled 23 Russian diplomats (an action which would later be responded to with a Russian expulsion of 23 British diplomats), British Foreign Secretary Boris Johnson said on 16 March that it was "overwhelmingly likely" Putin had personally ordered the poisoning of Skripal. Putin's spokesman Dmitry Peskov called the allegation "shocking and unpardonable diplomatic misconduct".