South Korean President Lee Myung Bak on Tuesday ordered the country's military to remain vigilant after the weekend sinking of a navy vessel near the maritime border with North Korea in the Yellow Sea, dpa reported.
"Given that the sinking took place at the very front line with North Korea, the military should remain alert thoroughly against any possible move by the North," Lee said at the weekly cabinet meeting, according to his spokesman Park Sun Kyoo.
The president's comments came as the navy engaged in last-ditch efforts to rescue 46 sailors still believed trapped in the ship that sank Friday.
"Today, we will try to drill a hole in the stern to open an access to the sunken vessel in the hope of discovering any survivors," a military official was quoted as saying by the Yonhap News Agency.
Hope of finding anyone alive, however, had diminished. Navy officials said they believed trapped sailors could have survived up to 69 hours. No signs of life were detected Monday evening when rescuers knocked on the hull of the ship's stern with hammers.
Defence Minister Kim Tae Young said Monday that old North Korean sea mines - remnants of the 1950-53 Korean War - might have caused the explosion that caused the ship's sinking. However, he later said one should not completely rule out that the modern North Korean military might have been involved.
Pyongyang has remained silent on the sinking.
"North Korea may have three reasons for its silence," Kim said in a meeting with lawmakers. "The North may try to conceal its possible involvement. Second, the North does not want to be misunderstood, if innocent. Or, third, it may try to maximize the provocation effects. In either case, we need to remain cautious in our reaction."
Fifty-eight crew members survived the sinking of the 1,200-ton Cheonan on Friday after an unexplained explosion in the rear of the ship, but 46 remained missing.
The front of the ship was located Sunday, but the rear section was only found Monday.
Friday's sinking occurred near the disputed maritime border with North Korea in the Yellow Sea. The area was the site of naval clashes between the two countries in 1999, 2002 and 2009.