On Friday, a top State Department official who has served in the Obama and Trump administrations announced that gains against the Islamic State have picked up sharply and that the militants have lost 78 percent of their territory in Iraq and 58 percent in Syria. The Washington Post’s headline (which the White House circulated in an email): “Under Trump, gains against ISIS have dramatically accelerated.” Then, on Saturday, China and Russia joined in a unanimous U.N. Security Council vote to approve a U.S.-sponsored resolution with tough new sanctions on North Korea, a forceful world response to that country’s missile tests. These two developments, in addition to being successes, had another thing in common: In both cases, the Trump administration essentially embraced Obama administration policies — policies Trump previously derided as a “total failure.” The Trump administration, at least temporarily, shelved the president’s bellicose rhetoric, made some tweaks to his predecessor’s strategies and pursued a course of relative continuity.