LONDON (AP) — Britain sanctioned Russia’s GRU intelligence agency and summoned Moscow’s ambassador on Thursday after an inquiry concluded that President Vladimir Putin was responsible for a nerve agent attack on British soil in 2018.

The government said that GRU was being sanctioned in its entirely over the attack in the city of Salisbury that targeted Sergei Skripal, a former Soviet agent who had defected to Britain.

A British woman, Dawn Sturgess, died after coming into contact with the Novichok nerve agent.

Former U.K. Supreme Court Justice Anthony Hughes, who led an inquiry into Sturgess’ death, said that the attack on Skripal “must have been authorized at the highest level,” by Putin.