The United States said Monday it would judge North Korea by its actions as it declined to speculate on the implications of the removal of the secretive communist nation's army chief.

White House spokesman Jay Carney, traveling with President Barack Obama to Ohio, was asked about North Korean state media's announcement on Ri Yong-Ho, previously considered a confidant of the country's young leader Kim Jong-Un.

"The way we address the issue of policy towards North Korea has to do with holding North Korea accountable to its international obligations and judging North Korea by its actions and not spending a lot of time trying to read into personnel moves in what is one of the world's most opaque governments and societies," Carney said.

Carney was referring to North Korea's pledges in stalled six-nation talks to give up its nuclear program and UN Security Council resolutions that call on the communist state not to conduct nuclear or missile tests.

South Korea has described North Korea's sudden announcement of the army chief's removal as highly unusual and said it would keep a close eye on its neighbor.

Ri had been seen as a hardliner inside North Korea and at a massive rally in March declared a "sacred war" against South Korea for allegedly insulting the leadership in Pyongyang.

Ri was one of the key figures who supported the untested Kim, who is in his late 20s and took over the nuclear-armed nation after the death of his father Kim Jong-Il in December.

State media said that Ri quit all posts due to illness. Analysts suspected that Ri fell out of favor with Kim or that the new leader was trying to exert his authority.

North Korea on April 13 carried out a defiant rocket launch, which even Pyongyang's state media acknowledged was unsuccessful.