North Korea fired two ballistic missiles in a northeastern direction Monday, media reports said.

South Korea claimed one of the missile launches possibly failed and fell inland within the country.

The Joint Chiefs of Staff (JCS) told Yonhap news agency one short-range ballistic missile was launched from the Jangyon area in South Hwanghae Province at about 5:05 a.m. and flew about 600 kilometers, landing in waters off the North's northeastern city of Chongjin.

Another ballistic missile was launched from the same area at around 5:15 a.m. and flew only about 120 kilometers, before its trail disappeared from radar, the South Korean news agency reported.

Col. Lee Sung-jun, spokesperson of the JCS, told a briefing the second missile may have flown abnormally during the early stage of its flight and that if it exploded in midair, its debris could have fallen inland.

"We are conducting a comprehensive analysis on various possibilities," Lee was quoted as saying by Yonhap, when asked if the missile had exploded or fallen inland.

A JCS official said the missile, which failed, probably fell towards Pyongyang city.