A North Korean rocket carrying the country’s second spy satellite exploded midair on Monday, the Associated Press reports. The rocket reportedly blew up soon after liftoff due to a suspected engine problem, according to the South Korean military, which said it detected debris falling over North Korean waters two minutes after liftoff. The explosion prompted Japan’s government to briefly tell its citizens to take cover and seek shelter. This is just the latest blow to North Korean leader Kim Jong Un’s plan to launch military reconnaissance satellites that would monitor the U.S. and South Korea. North Korea sent its first such spy satellite into orbit last November—following two failed liftoffs—and the country plans to launch at least two more this year alone. And while Kim has maintained that North Korea has the right to launch satellites and test missiles, Japanese Defense Minister Minoru Kihara called North Korea’s plans “a serious challenge to the entire world,” while South Korea’s Unification Ministry deemed it “a provocation that seriously threatens our and regional security.”