The top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong-il's five-day trip to China was officially made known by state media on both sides only after he had wrapped up the visit.

The nature of the visit had aroused keen speculation even as the global media gave detailed reports about every stop in Kim's tour itinerary.

In fact, the visit from May 3 to 7 turned out to be an open secret.

In February, China officially invited Kim Jong-il, the chairman of the National Defense Commission of the DPRK, to visit the nation again at his convenience.

This indicated that Beijing did not want the visit to be seen as veiled in secrecy. It also showed that China had prepared well in advance to receive Kim at any time.

From the perspective of international relations, Pyongyang showed high political wisdom in the timing of this unofficial visit.

First, the Nuclear Non-Proliferation Treaty (NPT) Review Conference was taking place at the United Nation's (UN) headquarters in New York on May 3, the same day that Kim began his tour of China.

The conference was represented by more than 140 countries and regions jointly upholding the authority of, and strengthening the NPT framework.

This conference, together with the first nuclear safety summit held last month in Washington, which saw participation by 47 heads of state and international organizations, indicates that the international community has realized that issues concerning nuclear proliferation and nuclear safety have become real threats to human survival.

As a state that once acceded to the NPT and later withdrew from it, the DPRK is facing tremendous pressure. So amid such a backdrop, its leader's China trip left the international community guessing. Pyongyang had played a tactical card.

Second, the sinking of a Republic of Korea (ROK) warship in March, which killed 46 sailors, shocked Seoul as well as the global community.

Although the results of the investigation have not yet been officially announced, Seoul gave strong indications that it believed the DPRK was involved in the incident.

The ROK will take up the matter with the UN once the probe concludes. Then, as a permanent member of the UN Security Council, China's stance would become critical.

When he was here for the opening ceremony of the Shanghai World Expo on April 30, ROK President Lee Myung-bak held talks with President Hu Jintao on several important regional issues including the "Cheonan" investigation.

Kim Jong-il arrived in China soon after Lee left. The timing and the courteous reception Kim received agitated some in the ROK, as it appeared (to them) that China had taken the side of the DPRK in the inter-Korean confrontation.

On May 3, ROK's First Vice-Foreign Minister Sin Kak-soo summoned Zhang Xinsen, the Chinese ambassador to the ROK, to express Seoul's position on Kim's China trip.

Summoning the Chinese ambassador over a specific case was a rare gesture by the ROK government.

It is understandable that Seoul felt uncomfortable over the timing of the DPRK leader's trip to Beijing.

Even so, such a strong reaction reflects Seoul's misunderstanding of China's role in the Korean Peninsula dispute. The fact is, China has long been striving for peace and stability in the peninsula.