Ri Su-yong's recent visit to China is the first by a high-ranking North Korean politician since the UN Security Council adopted the toughest sanctions ever against North Korea in March. The high-profile delegation led by Ri, former minister of foreign affairs but now vice chairman of the seventh Central Committee of the Workers' Party of Korea (WPK), has garnered wide attention.

On the surface, Ri visited China with the purported goal of reporting on the outcome of the just concluded seventh Congress of the WPK. But the real purpose is to break away from the sanctions by seeking a breakthrough in China.

The fourth nuke test by North Korea in January has reinforced Pyongyang's determination to own nuclear weapons. Such an ambition has been harshly countered by the joint efforts of the UN Security Council. China has shown support for sanctions against North Korea and other previous UN resolutions about North Korea. Beijing has already put a lot of effort in adopting concrete measures.

Pundits and scholars have varied opinions about the current Sino-North Korean ties. When I was in New York recently for a seminar, the director of a US think tank said China needs North Korea more than North Korea needs China, because Beijing doesn't want Pyongyang to fall apart.

Such a challenging view seems out of line with the facts. China is way stronger than North Korea in all areas, especially foreign relations and the economy. Isolated by the international community and afflicted by long-standing economic depression, North Korea has a lot to ask from China, not vice versa.

But for a long time, Pyongyang may try to make Beijing believe in its importance to China so as to benefit from the bilateral relationship. For years, this idea has left less wiggle room for China to deal with North Korea-related issues, and so China always resorts to compromises.

Regarding the current Sino-North Korean relationship, whether North Korea is still China's "buffer zone" is a question that cannot be evaded. In the Cold War, North Korea was indeed a buffer zone for China's national security, but 20 years have passed since the iron curtain lifted, and the global landscape has gone through a makeover.

In the Korean Peninsula, the South is rising and developing, while the North is declining and lagging behind. It is not hard to identify which development model is more progressive.

South Korea has also become a pivot in China's foreign relations. Since China's transfer of leadership in 2012, China and South Korea have ramped up their relationship to an unprecedented level, while the Sino-North Korean relationship remains cold, and the top leaders of the two sides have not met with each other.

Given the expansion of globalization and the wide use of unmanned planes, the "buffer zone" idea is outdated and sticking to it may be a sign of a Cold War mentality.

In the past 20 years, North Korea has been wheeling and dealing in an attempt to be a nuclear power. The closer it gets to this goal, the more likely there will be a nuclear disaster. China will bear the brunt if nuclear leaks or accidents occur in North Korea.

Given this scenario, China would rather embrace a "capitalist" South Korea than accept a "socialist" and nuclear North Korea. People have been talking about a North Korean collapse for over 20 years, but it hasn't happened. People are probably too worried about this.

Therefore, it is not a rising China that should cozy up to North Korea. Instead, while facing a serious problem of survival, North Korea needs to appeal to China for help.

Reluctant to give up its nuclear programs, Pyongyang must be feeling the rising pressures caused by the economic sanctions. Thus, Pyongyang hopes Ri could convince China to relax the sanctions, but it won't be easy.

The author is a professor at the Institute of International Studies, Fudan University. opinion@globaltimes.com.cn Follow us on Twitter @GTopinion