As British authorities continue their investigation into the terrorism incident at RAF Fairford base, the nation’s intelligence services are warning of a “major shift” in Iranian strategy.

Sir Ken McCallum, director general of MI5, explained this observation during his annual threat update at Thames House on Tuesday. After speaking about threats posed by Russia and China — declaring that the former remains “aggressor number one” — McCallum turned his attention to Iran’s recent efforts toward “subcontracting its UK violence.”