President Trump became the first national leader to call for protecting the U.S electric and communications grid against an electromagnetic attack like one practiced in North Korea. Deep in his new national security strategy released this week, he made good on a campaign promise to move quickly to make the fixes that proponents have long called for. Two of the chief advocates, William R. Graham and Peter Vincent Pry, executives of the nation’s first Congressional EMP Commission, said in a statement, “President Trump understands, even if everyone in his administration does not, that ‘strategic stability’ and ‘longstanding strategic relationships with...