Timing of any future provocative act by North Korea depends on the health of its leader, Kim Jong Il, the top U.S. military commander in the Pacific said.
Adm. Robert Willard, speaking at a briefing in Washington Tuesday, said the United States is monitoring North Korea for signs that the reclusive nation may be planning aggressive actions in light of its succession process, Stars and Stripes reported.
Western leaders said they believe Kim Jong Un, Kim's son, has been designated the next ruler of the country.
"We try to determine the succession dynamics that are ongoing, especially as we approach 2012, which the North Koreans have declared as an auspicious year for themselves and what that may portend in terms of Kim Jong Un's leadership position," Willard said.
A North Korean torpedo sank the South Korean warship Cheonan in March 2010, killing 46 sailors and heightening tensions between the two countries. In November 2010, North Korea attacked a South Korean island, killing two South Korean marines and two civilians.
Recently, however, North Korean officials signaled an interest in resuming six-party international talks about the country's nuclear program.
In the past, North Korea's succession process has led to provocations as the possible new leader attempts to establish his credibility with the North Korean military, Willard said.
He noted Kim Jong Un's presence during the 2010 attacks "was not lost on us."
Willard said attitudes in South Korea toward its northern neighbor have "fundamentally changed."
"There is very strong...intolerance at this point for any further provocations," he said.