Kim Jong Un has supervised a live artillery drill amid heightened rhetoric against the United States and South Korea, North Korea’s state news agency says. KCNA did not mention when the drill took place, but said two artillery units on islands near a disputed sea border with South Korea had hit their targets, according to Reuters. North Korea has been threatening a nuclear war with the United States after it was targeted by the U.N. for sanctions over a long-range missile test. South Korean workers also have reported seeing North Korean soldiers wearing camouflage webbing this week. But observers doubt that North Korea could stage a nuclear attack on the U.S., Reuters reports.