South Korea's YTN TV network said the government was investigating whether the sinking was due to a torpedo attack by the North, and Yonhap news agency said the Seoul government had convened an emergency meeting of security-related ministers.
Yonhap also reported a South Korean navy ship firing toward an unidentified vessel to the north.
North Korea in recent weeks has said it was bolstering its defenses in response to joint South Korean-U.S. military drills that were held this month.
In additions to this morning's vessel sinking, North Korea has also issued a new warning of "unprecedented nuclear strikes" against S. Korea and the United States. Though the North issues these warnings from time to time, the news of this morning's possible torpedo strike suggest an aggressive stance:
"Those who seek to bring down the system in the (North), whether they play a main role or a passive role, will fall victim to the unprecedented nuclear strikes of the invincible army," North Korea's military said in comments carried by the official Korean Central News Agency.
The North, believed have enough weaponized plutonium for at least half a dozen atomic bombs, conducted its second atomic test last year, drawing tighter U.N. sanctions.Stay tuned as this story develops...