Pyongyang had intended to use the spacecraft to track US troops
North Korea has said that its would-be first military spy satellite crashed into the Yellow Sea after the rocket carrying it suffered an engine failure.
According to the Korean Central News Agency (KCNA), the rocket, which was launched on Wednesday, lost thrust due to "the abnormal staring" of the engine following first-stage separation. North Korean officials were quoted as saying that engineers would study "the serious defects," after which another launch would be attempted "as soon as possible."
The South Korean Joint Chiefs of Staff (JCS) confirmed that Pyongyang fired a "space launch vehicle," adding that the projectile fell around 200 kilometers (124 miles) west of the island of Eocheong.
Sirens were blasted across Seoul early on Wednesday, but government officials later said that the alert system was activated by mistake.
Warnings also were issued over the emergency alert system in Japan's southern prefecture of Okinawa. However, the Japanese government later said the rocket did not fly over the country's territory. According to NHK, Pyongyang warned the Japanese Coast Guard on Monday that the satellite would be launched between Wednesday and June 11.
Senior North Korean official Ri Pyong-chol announced on Tuesday that Pyongyang plans to launch its first spy satellite, saying it would be fired sometime in June. Ri said the satellite was needed to counter growing hostilities from Washington and "reckless" joint military drills by the US and South Korea.
The US has stated in the past that a satellite launch by North Korea would violate the international sanctions imposed on Pyongyang's ballistic missile program.