A newly tested North Korean short-range ballistic missile appears to be a copy of an advanced Russian design that could greatly improve Pyongyang’s ability to evade U.S. missile defense systems, according to U.S. officials. President Trump, who has sought unsuccessfully for the last year to persuade North Korean leader Kim Jong Un to give up his nuclear weapons, has dismissed the new missile as “very standard stuff.” But military and national security officials see a potential threat to U.S. forces and allies in northeast Asia.