The United States and its allies in the Asia-Pacific region are planning a "wide range of options" for a possible leadership change in North Korea, a top US military commander said Wednesday.

"We are prepared to execute a wide range of options in concert with allies in South Korea and in discussions through State (Department), which would have the lead, with countries in the region and internationally if necessary," said Admiral Timothy Keating, the top US commander in the Asia-Pacific region.

North Korean leader Kim Jong-Il is widely believed to have suffered a stroke last August and speculation has flared about his deteriorating health.

State television earlier aired a documentary in which the "Dear Leader" barely used his left hand and seemed to have trouble with his left leg.

Kim's health is the subject of intense international attention amid uncertainty about who will succeed him at the helm of the impoverished communist nation and its nuclear and missile programs.

"I don't think it is axiomatic that the departure of Kim Jong-Il means a national security crisis. We would hope it wouldn't. But we are going to be prepared if it does mean that," said Keating.

South Korean intelligence officials have been quoted as saying Kim, 67, has nominated his youngest son Jong-Un, 26, as successor, but no announcement has been made.

"What he has in mind on a day-to-day basis -- not crystal clear to any of us," Keating told reporters.

"What would happen if and when he cedes control or is no longer capable of exercising control -- don't know," the US Pacific Command chief added, noting however, that the US military posture would not change should Kim be replaced.

"I can tell you that we have plans with the United States Forces-Korea and others in place if the president tells us to execute those plans, in the event of some uncertain succession in the North."

Keating also said he would be "very concerned" if North Korea were trading weapons or other banned cargo with the military junta in Myanmar in violation of United Nations Security Council Resolution 1718, after US Secretary of State Hillary Clinton earlier warned about possible nuclear cooperation between the two countries.

A US Navy destroyer last month tracked the North Korean-flagged Kang Nam 1, which was believed to be headed for Myanmar, suspected of carrying a cargo of weapons.

But the cargo carrier eventually turned back, for reasons Keating said he was not aware of.

"It's not crystal clear to anybody, to the best of my knowledge, outside of North Korea, why the instructions were given for the ship to return to its port of origin," he said.

Keating noted, however, that "we have the capability of keeping close track of any sort of vessel that might be violating UNSCR 1718."

And citing hope for a "more robust dialogue, something substantive" on military ties between Washington and Beijing, Keating said he would attend high-level US-China talks in Washington early next week.

Beijing has played a key role in efforts at both multilateral talks and the UN Security Council to rein in Pyongyang's nuclear ambitions and bring it back to the negotiating table.