President Donald Trump’s brinkmanship with Iran is on the boil, spilling beyond diplomacy to a planned air attack on Iran that Trump said he ordered, then pulled back at least for now. This, as the U.S. undertakes an unusual troop deployment to the Mexican border , tends its nearly two-decade-old war in Afghanistan and grapples with stalled talks with North Korea over its nuclear weapons program. Through it all, the U.S. has no defense secretary , but rather an acting one who is taking over from another acting one, who suddenly quit. And the latest one, Army Secretary Mark Esper, who takes over Sunday, might only be able to serve as acting Pentagon chief for less than two months under the rules, requiring yet another short-term boss before it’s all sorted out. On Friday night, Trump officially announced he intended to nominate Esper for the permanent job. Temporary leadership is a hallmark of Trump’s administration . “It gives me more flexibility,” Trump has said of the many people in acting leadership jobs, not always by his choice. The practice lets Trump quickly, if temporarily, install allies in important positions while circumventing the Senate confirmation process, which can be risky with Republicans running the chamber by a slim 53-47 margin. But the Senate Democratic leader, Chuck Schumer of New York, says it’s out of hand. “With everything going on in Iran and all the provocations and counteractions, and to have no secretary of defense at this time is appalling,” he said….