A day after North Korea test-fired 25 rockets from its east coast, the mobile launchers remained in place on Monday, a potential sign of additional provocations, a military source said.



The latest move comes as South Korea has increased military vigilance in the wake of the North's rocket launches, seen as a show of protest against ongoing joint military drills between Seoul and Washington.



"About 10 mobile launchers are seen (in satellite images) near Wonsan in Kangwon Province, where the North fired short-range rockets yesterday," the source said, asking for anonymity as he is not authorized to speak to media. "The military is closely watching (the North Korean military) to prepare for possible additional launches."



The South Korean military judged the rockets to be FROG short-range surface-to-surface missiles, which the North introduced in the 1960s. The 9.1 meter-long rocket flew about 70 km before hitting the water, the defense ministry said.



The spokesman for the defense ministry said the trajectory of Sunday's rockets indicated they are FROG missiles, adding the South Korean military had detected its moves ahead of the launches.



"North Korea launched a larger-than-expected number of rockets yesterday," Kim Min-seok said in a briefing. "The military is currently looking into its intention but currently considers (the rocket launch) as a provocative act in a show of force."



Kim condemned Pyongyang's firing of rockets without declaring a no-fly, no-sail zone, potentially endangering civilian vessels or flights in their paths.



"North Korea should stop raising military tension and provocations that cause concerns to the neighboring nations," Kim said.



The latest rocket launch came two days after the North's National Defense Commission threatened to demonstrate its nuclear deterrence capability against the U.S. hostility.



The spokesman added that the communist state was already ready to conduct a fourth nuclear test, though it has shown no imminent sign.



Pyongyang carried out atomic tests in 2006, 2009 and in February last year. (Yonhap News)







