SEOUL - The Democratic People's Republic of Korea (DPRK) appeared to have failed in its fourth test-launch of an intermediate-range Musudan ballistic missile after its dialogue overtures on military matters were repeatedly dismissed by the Republic of Korea, Seoul's military said Tuesday.

An official at the ROK's defense ministry told Xinhua on the phone that the DPRK tried to test-fire one unidentified missile at about 5:20 am local time from its Wonsan area in its east coastal region.

The official said the test-launch was estimated to have failed, adding that Seoul's military is analyzing details. He noted that the ROK's military has been maintaining complete preparedness for possible launches of additional missiles.

According to a government official of the ROK , cited by Yonhap news agency, Seoul's military believed that it was the Musudan ballistic missile which is known to be capable of hitting part of the US territory such as Guam and the outer reaches of Alaska.

The DPRK test-launched three Musudan missiles this year alone, two on April 28 and one on April 15 each, but all of the three test-firings were believed to have failed as the missiles exploded in mid-air or crashed in waters several seconds after lift-off.

The April 15 launch was the DPRK's first known test-firing of the intermediate-range ballistic missile. Pyongyang has allegedly deployed the Musudan missiles since 2007.

The missile is considered especially threatening as it is fired from a mobile launcher, making it hard to detect and track in times of military conflicts. It can also carry a nuclear warhead.

As all of the three test-firings ended as failure, the DPRK was widely expected here to conduct another test-launch to prove its nuclear-tipped ballistic missile technology.

The ROK's government official was quoted by Yonhap as saying that the fourth launch appeared to have failed as the missile was estimated to have exploded on its mobile launcher even before take-off.

The ROK's military estimated that the DPRK had deployed an unspecified number of Musudan missiles on the Wonsan area, which were closely tracked and monitored by military authorities of the ROK and the United States.

The fourth test-launch was in line with top DPRK leader Kim Jong-un's order on March 15 to test a nuclear warhead and ballistic rockets capable of carrying the warhead "in a short time".

After the seventh ruling Workers' Party of Korea (WPK) congress that last four days through May 9, the DPRK repeatedly made dialogue overtures toward South Korea to talk about military matters in order to defuse tensions on the Korean peninsula.

Seoul, however, rejected the proposals as Pyongyang failed to mention its willingness to denuclearize. the ROK held fast to its position that no dialogue will be held with the DPRK unless Pyongyang shows its denuclearization will through sincere actions.