May 20, 2010 Stratfor:
An international probe found that North Korea attacked the ChonAn warship with a heavy torpedo in March, South Korea announced, Yonhap reported May 20. An international team of experts reached the conclusion after scrutinizing the wreckage of the 1,200-ton patrol ship and other evidence collected from the scene, including North Korean torpedo parts. The team confirmed that a few small submarines and a mother ship supporting them left a North Korean naval base in the West Sea 2-3 days prior to the attack and returned to port 2-3 days after the attack.