Western powers must make a “collective” effort to crackdown on Russian military intelligence operations, British Prime Minister Theresa May said Wednesday.

May announced the indictment of two officers of Russia’s GRU in connection to the use of a chemical weapon to poison a Russian double agent in Salisbury, England, which resulted in the death of one woman who was subsequently exposed to the poison by accident. The incident punctuated May’s call for a broader Western effort to diminish the spy agency.