Panetta, South Korean defense chief confer about North Korea

The call lasted about 15 minutes, Little said.

“Both men agreed that it was critical to remain prudent with respect to all matters related to our security posture there, and pledged to keep one another informed in the coming days,” Little said.

North Korean media announced late Sunday evening that the 69-year-old dictator had died.

It remains unclear whether Kim Jong Il’s son, Kim Jong Un, will be able to take control of the nuclear-armed nation. The military and other powerful factions are seen by regional observers as potentially ready to grab power in the post-Kim Jong Il era.

In a separate statement, U.N. Secretary General Ban Ki-moon extended "his sympathy to the people of [South Korea] at this time of their national mourning."
"The secretary-general reaffirms his commitment to peace and security on the Korean peninsula," according to the U.N. statement. "The United Nations system will continue to help the people of [South Korea]. The secretary-general is closely following the situation."

—This story was updated at 12:47 p.m.