SEOUL, July 9 -- The Democratic People's Republic of Korea (DPRK) appeared to have failed in the test-firing of a submarine-launched ballistic missile (SLBM), Yonhap news agency reported on Saturday, citing South Korea's Joint Chiefs of Staff (JCS).

The JCS was quoted as saying that what was believed to have been a SLBM was fired at about 11:30 a.m. (0230 GMT) in waters southeast of the DPRK's eastern port city of Sinpo in South Hamgyong province.

The missile was normally ejected from a 2,000-ton DPRK submarine and was successfully ignited. But it was estimated to have exploded in mid-air at an altitude of about 10 km, flying just several kilometers, according to the JCS analysis.

It marked the DPRK's first test-launch of its SLBM since April 23 when a ballistic missile fired from a submarine flew some 30 km before exploding and fragmenting into two to three pieces.

The launch came a day after Seoul and Washington jointly announced their decision to deploy the Terminal High Altitude Area Defense (THAAD) in the U.S. Forces Korea (USFK) to better tackle what they claimed is the DPRK's nuclear and missile threats.