The heads of MI5 and the FBI have issued an unprecedented joint warning that the threat of a domestic terrorist attack could rise as a result of the crisis in the Middle East. The counter-terror chiefs said Jewish communities and organisations, as well as other groups, may face a heightened danger from lone actors, Hamas militants and Iran, a supporter of Hamas, on British or US soil. Ken McCallum, the director general of Britain’s domestic spy agency, MI5, said there was a risk that “self-initiated” individuals who may have been radicalised online might respond in “spontaneous or unpredictable ways” in...