Since the imposing of United Nations sanctions against North Korea after its second nuclear test on May 25, everyone has been looking toward China for its response. Publically, China has been insisting that it is with the United Nations and will impose all the recent resolutions passed against North Korea.

However, ground realities and political and strategic calculations might force China's hand in another direction.

For the first time, the Chinese have been literally ``shocked" by a North Korean nuclear test. Conducted merely 50 miles from the Chinese border, it literally shook the whole of Northeast China.

Many schools and government buildings needed to be evacuated for fear of an earthquake. This has led many Chinese to now realize the North Korean nuclear threat might be closer to home than they had previously thought.

Chinese political and academic elites have become seriously engaged in debate on the pros and cons of having a nuclear North Korea on its borders.

China has long and historical relations with its neighbor. After World War II, even though it was the Soviet regime which brought up the communist regime in North Korea, it was the Chinese who came to North Korea's rescue during the 1950-53 Korean War.

But for this Chinese intervention, North Korea might very well have become a footnote in history books.

Again after the collapse of the Soviet Union and communism in Eastern Europe, when the North Korean regime lost all its traditional trade and aid partners, it was China that came to North Korea's rescue.

Without Chinese support at that critical juncture, North Korea might itself have collapsed.

Currently, China is said to have become North Korea's biggest trading partner. According to one conservative estimate, the annual economic exchange between the two countries might have crossed over the $2-billion mark at the end of 2008.

China has emerged as North Korea's main supplier of goods, from domestic appliances, fuel, fertilizers and shoes to everything in between, which is essential for running the North day-to-day. By some estimates, China's economic aid to the North might have quadrupled over the past five years.

Regardless of what the United States would like to believe, China does not share the American strategic interest in North Korea. Its interests are in fact much different. For example, the United States is mainly concerned with North Korea's nuclear and missile program and human rights issues.

China's interests in the North, however, are much broader and include economic, political, security and strategic calculations. Thus, there is a limit to what the United States can reasonably expect China to agree to in dealing with the country.

Currently, China is following a two-pronged strategy. On one side, it is trying to support the U.N.-sponsored sanctions, thus keeping the United States and its allies in good humor.

At the same time, it is making sure North Korea doesn't take too much pressure from what is happening at the international level, while maintaining business links.

For China, these are difficult times. It finds itself placed between a rock and a hard place. Its outright support of North Korea could cause serious damage to the growing Chinese profile as a law-abiding member of the international community ― not to mention the potential damage to growing economic relations with the United States and Europe.

Yet, China's direct support of U.S.-led sanctions could also compromise its core strategic and economic interests at home and in the region.

Given the recent dependence on China for its economic survival, the genuine and whole-hearted implementation of U.N. sanctions could in fact jeopardize the North as an entity.

The potential economic and strategic consequences of a sudden collapse of the North Korean regime is what is making the Chinese leadership think twice about going along with the U.S. demands for sanctions.

Economically, the sudden collapse of North Korea could prove very disastrous for the Chinese economy. It would not only bring millions of poor and unskilled North Korean refugees into its territory, but it would also seriously threaten peace and stability on its borders, which it is so seriously seeking in order to help sustain its continued economic expansion.

A sudden collapse scenario could also leave the nuclear weapons in North Korea up for grabs. The possibility of nuclear weapons in rogue hands on the other side of its borders would pose a serious threat to China's security.

The sudden failure of the North Korean regime even has the potential to turn the present balance of power upside down.

Without North Korea as a buffer state, leaving the South Korean government to take the entire peninsula under its own sway, China could find U.S. forces standing right on its very border, something the current Chinese leadership likely deems ``unthinkable."

Thus, there is a limit to how much China can go along with the U.S.-led sanctions to pressurize North Korea into giving up its nuclear weapons and returning to six-party talks. It will only go along with the United States to the extent that the survival of North Korea is not threatened.

The moment sanctions were to actually pose such a threat, China would be forced to go its own way. In this era of economic downturn, when million of Chinese are losing jobs, a collapsed state, chaos or even war on its border is simply an unthinkable outcome of the present situation to the leadership.

It cannot be overstated that the strategic and economic interests of China are much different than those of the United States. It is common wisdom in East Asia that without China's genuine and whole-hearted support, the idea of sanctions and directly pressuring North Korea will just not work.

And China is just not ready or willing to go along with the wishes of the United States in this matter. In the distant future, one could imagine China leaning diplomatically on its North Korean neighbor to give up nuclear weapons.

But it will eventually do it its own way and for its own reasons. In short, China will never be able to fully support U.S. policy in the region.

Under pressure from the international community, China implemented the cutting-off of oil supplies to North Korea in 2003 and 2007. This tactic did not work then, and there is no reason to believe it will work now.

The United States and its allies should not expect too much from U.N.-sponsored sanctions on North Korea. In the short and medium term, they are not going to have any serious impact on North Korean regime or its economy.

Given the ground realties in the region and failure of multilateral talks to produce tangible results, serious direct diplomatic engagement with North Korea might be the only practical solution to the growing complicated problem here on the Korean Peninsula.

Former U.S. President Bill Clinton made a good start of direct diplomatic engagement with North Korea by sending his secretary of state to engage the North Korean leadership.

President Brack Obama would do well to pick up from there and send his own secretary of state to Pyongyang for direct and face-to-face talks.

* The artcile was orginally published in Korea Times on June 30 and can be seen
at http://www.koreatimes.co.kr/www/news/opinon/2009/06/137_47612.html