The reclusive communist country was also reportedly bolstering it defenses and conducting amphibious assault exercises along its western shore, near disputed waters where deadly naval clashes with the South have occurred in the past.
South Korea's Yonhap news agency said the missile had been sent by train to the newly completed missile facility of Dongchang-ni, about 40 miles from the Chinese border.
Yonhap, quoting government sources, said the missile could be ready to launch in a week or two. South Korean media have speculated that the North wants to time the launch for around June 16, when South Korean President Lee Myung-bak has a summit in Washington with President Barack Obama.
Read the Analysis by AP HERE.