North Korea has deployed one or two mid-range ballistic missiles to the eastern city of Wonsan ahead of a possible launch, news reports said Thursday.
The Musudan missile, or missiles, were deployed 20 days ago in the vicinity of Wonsan's Hodo Peninsula, a source told South Korea's Yonhap News Agency.
"North Korea is likely to venture a launch on the occasion of Kim Il-sung's birthday," the source was quoted as saying.
The birthday of the late North Korean founder and leader is Friday.
"Our military is closely following the possibility of North Korea's fifth nuclear test or launches of ballistic missiles like the Musudan," South Korean Defense Ministry spokesman Moon Sang-gyun told a press conference.
North Korea held its fourth nuclear test explosion in January and launched a long-range rocket in February, prompting the UN Security Council to impose its strictest sanctions ever on Pyongyang.