– North Koreans had long known Jang Song Thaek as the No. 2 figure in their country, the revered uncle and mentor of Kim Jong Un, the paramount leader. Then on Monday, state-run television showed two green-uniformed guards clutching a glum-looking Jang by the armpits and pulling him from a meeting of the ruling party after he was denounced for faction-building, womanizing, gambling and other acts as dozens of former comrades watched.

The spectacle of Jang's humiliating dismissal and arrest was a highly unusual glimpse of a power struggle unfolding inside the nuclear-armed country. But nowhere is the downfall more unnerving than in China.

North Korea's longtime protector and economic lifeline, China has considered strategically close relations with North Korea a pillar of foreign policy and a bulwark against the U.S. military presence in South Korea. Despite Chinese irritation with North Korea's nuclear tests and other bellicose behavior, China had built a good relationship with Jang as the trusted adult who would monitor Kim, who is less than half his age.

Any shift by China concerning North Korea has the potential to significantly alter the political equilibrium in Asia. While there is no indication that the Chinese intend to change their view, it seemed clear that even Beijing's top leaders were surprised by Jang's abrupt downfall Sunday, and even more on Monday by the North Korean state television broadcast.

"Jang was a very iconic figure in North Korea, particularly with economic reform and innovation," said Zhu Feng, professor of international relations at Peking University, and a specialist in North Korea. "He is the man China counted on to move the economy in North Korea. This is a very ominous signal."

Jang's dismissal was a shock not only because he had long been considered a core member of the country's ruling elite and a regent and confidant of Kim, who assumed power only two years ago upon the death of his father, Kim Jong Il. The way that Jang was dismissed also was considered extraordinary, as the North Korea government has almost always maintained secrecy over its inner workings during the more than 60 years of rule by the Kim family.

"Kim Jong Un was declaring at home and abroad that he is now the truly one and only leader in the North, that he will not tolerate a No. 2," said Yang Moo-jin, an analyst at the University of North Korean Studies in Seoul, South Korea.

Jang had visited China on several occasions and had been considered the most important advocate of the Chinese style of economic overhaul that the government in Beijing has been urging North Korea to embrace.

At 67, Jang is of the same generation as China's leaders. Unlike the 30-year-old Kim — who has not been to China and who remains a mystery despite the lineage to his grandfather, North Korea's revolutionary founder, Kim Il Sung — Jang was seen by Beijing as a steady hand and a trusted conduit into North Korea's top leadership.

That the video of Jang's arrest Sunday at a Politburo meeting by military officers was released to the North Korean public, replete with tearful underlings shown denouncing him, was particularly unsettling for China.

China's official media gave prominent attention to the accusations against Jang, including some of the florid language used in North Korea's own state-run news media that recited the litany of his newly disclosed transgressions at party expense: womanizing, gambling, drug abuse and a politically motivated ambition to challenge Kim as the "unitary center." But also on the list was selling resources cheaply, an accusation that appears to have been aimed directly at China, the biggest buyer of North Korea's iron ore and minerals.

Now, the climate for Chinese investment in North Korea, which was not particularly good, would be likely to worsen, said Andrei Lankov, author of "The Real North Korea" and a professor of history at Kookmin University in Seoul.