SEOUL, South Korea (AP) — Air raid sirens have sounded on a South Korean island and residents evacuated to underground shelters after North Korea fired more than 20 missiles, at least one of them in its direction and landing near the rivals’ tense sea border. South Korea quickly responded by launching its own missiles in the same border area. The launches came hours after North Korea threatened to use nuclear weapons to get the U.S. and South Korea to pay what it called “the most horrible price in history” in protest of ongoing South Korean-U.S. military drills that it views as an invasion rehearsal. The White House says the United States has no hostile intent toward North Korea.