Arrest of North Korea's No 2 figure is cause for concern in Beijing

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 pulling a glum-faced Jang by the armpits from a meeting of the ruling party after he was denounced for faction-building, womanising, 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 the major impact may be outside. The video of Jang's arrest on Sunday at a Politburo meeting was released to the North Korean public, replete with tearful underlings shown denouncing him, was particularly unsettling for China.

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

Any shift by China concerning North Korea has the potential to significantly alter the political equilibrium in Asia, where the divided Korean peninsula has existed for more than 60 years. While there is no indication that the Chinese intend to change their view, Beijing's top leaders were surprised by Jang's abrupt downfall. "Jang was an iconic figure in North Korea, particularly with economic reform and innovation," says Zhu Feng, professor of international relations at Peking University. "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 two years ago upon the death of his father, Kim Jong-il. The way Jang was dismissed was also extraordinary, as the North Korea government has almost always maintained secrecy over its inner workings, power struggles and skulduggery during the more than six decades of rule by the Kim family.