WASHINGTON (AP) — Defense Secretary Jim Mattis on Sunday shot back at North Korea’s claimed test of a hydrogen bomb with a blunt threat, saying the U.S. will answer any threat from the North with a “massive military response — a response both effective and overwhelming.” Earlier, President Donald Trump threatened to halt all trade with countries doing business with the North, a veiled warning to China, and faulted South Korea for its “talk of appeasement.” The tough talk from America’s commander in chief and the retired Marine general he picked to oversee the Pentagon came as the Trump administration searched for a response to the escalating crisis.