May needs her party

As if we needed reminding, this past week has shown that the Islamist threat is a truly global problem. In the space of a few days, Isis claimed responsibility for attacks on London Bridge and Borough Market; and elsewhere, for the attack on the Iranian Parliament and the tomb of Ayatollah Khomeini in Tehran. It would be hard to think of more diverse targets than drinkers at London pubs on a Saturday night and the tomb of the theocratic Shia cleric who inspired the 1979 Iranian revolution. Yet for Isis there is logic. All are enemies: infidels, heretics, apostates.

The Tehran atrocity shows again that what we are witnessing is a civil war within Islam. To the Sunni militant, the enemy could be a girl at a music concert or a worshipper at a Shia mosque. Iran has been more involved than anyone in the Syrian civil war, sending its proxy armies to defend their country’s Shia ally in Damascus.