Op-ed: The British prime minister plainly recognizes the nature of the struggle. Her opponent in Thursday’s elections, Jeremy Corbyn, equally plainly does not. With Britain battered by three terrorist attacks in three months, and its security services having thwarted five more in the same period, Prime Minister Theresa May on Sunday morning set out the specifics of her intended strategy “to take on and defeat our enemies.” May’s succinct and determined statement, delivered hours after three terrorists killed at least seven people in a central London murder spree, raises two questions: Does her government have the will to fight back...