The dramatic ouster of the uncle of North Korea's young ruler has sidelined the reputed second-most powerful official in the secretive hierarchy but Washington is not banking on a radical shift in Pyongyang's nuclear policy.

Nor does the release of an 85-year old U.S. Korean War veteran over the weekend necessarily herald an improvement in chilly relations between Washington and Pyongyang that have gotten worse since young dictator Kim Jong Un took power.

But there will be intense scrutiny of the North Korean government's next moves, to watch whether it moves to release another American citizen it has detained for the past year. That could provide an opportunity for some diplomacy between Washington and Pyongyang, which remain utterly at odds over the North's development of nuclear weapons.

Accused of abuse of power, corruption and profligate living, Kim's uncle Jang Song Thaek was stripped of his official positions, including in the National Defense Commission, the government's top ruling body. State television on Monday showed him being grabbed by two security guards from a high-level party meeting, chaired by Kim.

Political machinations in North Korea's authoritarian system are typically conducted behind closed doors, which made Jang's public purging and humiliation highly unusual. Jang had been viewed as a mentor to Kim since succeeding as dictator on the death of his father Kim Jong Il in December 2011.

It has been a generation or more since a North Korean ruler has conducted such a high-profile purge, but a senior U.S. official said Washington doesn't know whether this will have any impact on Pyongyang's nuclear policy and its relations toward the U.S.

Jang's ouster does not necessarily reflect instability in the North Korea, but it shows Kim Jong-un is further consolidating his power, said the official, who requested anonymity as he was not authorized to speak publicly on the U.S. government's reading of events in North Korea.

To the extent Jang's downfall affects the North's international relations, the impact is likely to be felt most keenly in Beijing as he was viewed as a front man for ties to China, its only major ally. Jang has been seen by outsiders as the leading supporter of Chinese-style economic reforms.

Yet the most telling message Jang's ouster conveys is about North Korea's internal dynamics.

Evans Revere, a former State Department official for East Asia, said it leaves no uncertainty about who is the sole source of legitimacy and command, and who is controlling government policy, including its twin goals, enshrined in the nation's constitution this year, to pursue both economic development and nuclear weapons.

That could extinguish any remaining hopes Kim's rise to power would herald reform of the authoritarian state _ hopes that were based on little more than his relative youth, education in Switzerland and enthusiasm for U.S. basketball.

Early on, his government reached an agreement with Washington for a nuclear freeze in exchange for U.S. food aid that was meant to pave the way for full-fledged negotiations on the North's nuclear program. But the North wrecked the deal within weeks when it launched a rocket in defiance of a U.N. ban. Tensions spiked further after an underground nuclear test explosion in February, which the North followed up with dire verbal threats against the U.S. and its allies for leading the push for tighter sanctions in response.

Those tensions have eased in recent months, and North Korea says it is ready to resume the six-nation negotiations on its nuclear program that it withdrew from five years ago. But given recent signs the North is restarting a mothballed reactor that can produce plutonium for bombs, Washington remains skeptical of Pyongyang's intent.

The North's detention of the two American citizens has only made matters worse.

One of the Americans, Korean War veteran Merrill Newman, who had been held since late October after visiting North Korea as a tourist, was freed on Saturday. North Korean state media explained he had apologized for his alleged crimes during the Korean War and because of his age and medical condition.

Washington welcomed the release, announced as U.S. Vice President Joe Biden was visiting neighboring South Korea, but is not reading into it any broader significance for U.S.-North Korean relations.

North Korea is still holding another American national, Kenneth Bae, who was arrested more than year ago and suffers health problems. He has been sentenced to 15 years on charges of subversion. Pyongyang shunned a previous offer by Washington to send a senior envoy to seek a pardon for Bae and his release.

Washington views Bae's detention as an obstacle to improving the U.S.-North Korean relationship and will now be pressing Pyongyang to resolve that case as well, although the U.S. official said progress in diplomacy on the North's nuclear program would still hinge on Pyongyang's willingness to honor its previous commitments on denuclearization. (AP)