A US commander acknowledged Wednesday that Washington has linked food aid to North Korea to progress on military issues, saying that the impoverished communist state needs to halt its nuclear program.

The US State Department has repeatedly denied it is tying politics to North Korea's requests for food and insisted it is only assessing humanitarian needs, amid reports by Christian aid groups of widespread hunger.

But Admiral Robert Willard, head of US Pacific Command, which covers Asia, outlined the conditions to food aid as he testified before Congress, where many lawmakers are skeptical of assistance to the hostile country.

"There are conditions that are going along with the negotiations with regard to the extent of food aid," Willard told the Senate Armed Services Committee.

Willard said "preconditions" for assistance "now include discussions of cessation of nuclearization and ballistic missile testing and the allowance of IAEA perhaps back into Yongbyon."

North Korea in 2009 kicked inspectors from the International Atomic Energy Agency, the UN nuclear watchdog, out of Yongbyon, the communist regime's key nuclear facility that was vital in developing atomic weapons.

The United States and North Korea last week held talks in Beijing aimed at resuming moribund six-nation nuclear negotiations. Washington has demanded Pyongyang commit to previous agreements on giving up its nuclear weapons.

The Beijing talks marked the first formal contact between Washington and Pyongyang since the December death of North Korea's leader Kim Jong-Il, who was succeeded by his young and untested son Kim Jong-Un.

Willard said the US military was watching closely for any "signs of instability or evidence that the leadership transition is faltering."

"For the time-being, the succession appears to be on course," Willard said.

The US commander said the younger Kim was surrounded by his father's aides and will likely "continue to pursue his father's coercive strategy," which includes the pursuit of nuclear weapons and complete control at home.

Five US aid groups, most with a Christian orientation, visited North Korea in 2009 and warned that food shortages were already so severe that some people were eating grass.

Some US lawmakers and South Korean officials accuse the North of exaggerating its needs to secure food. US diplomats say any American aid would likely consist of baby food and other items the military cannot easily divert.

Willard testified that North Korea "continues to pose one of the most likely and persistent threats to the United States" and its allies.