South Korea will be forced some day to choose between the United States and China despite its efforts to balance between the global giants, a renowned American pundit said Friday amid controversy over U.S. President Barack Obama's remarks on Seoul-Beijing ties.

After summit talks with President Park Geun-hye in Washington last week, Obama stated the U.S. expects South Korea to speak out against China if it fails to abide by international norms and rules.

Obama's message was viewed as thinly-veiled pressure on Seoul to join Washington in criticizing Beijing for its growing territorial assertiveness in the South China Sea.

In the end, South Korea will face a "painful decision" to pick one of the two, according to John Mearsheimer, professor of political science at the University of Chicago.

"The security competition in East Asia is going to increase in intensity over time. (South) Koreans are going be forced to choose at some point. That's what's going to happen," he said at a forum on South Korea's diplomacy hosted by the Korea National Diplomatic Academy.

In that case, he added, Seoul is bound to select Washington, as security considerations "always trump" economic considerations.

"Therefore, Korea's relationship with the United States will ultimately be more important than Korea's relationship with China," said Mearsheimer, who doubles as co-director of the program on international security policy at the school.

He said the rivalry between the U.S. and China over hegemony especially in Asia will continue to heat up and even risk a war.

"China will try to dominate Asia the way the United States dominates the Western Hemisphere. The U.S. is likely to go to greater length to prevent China from dominating Asia," the professor stressed.

He was skeptical that the two Koreas will achieve reunification in the foreseeable future, citing China's negative view.

"North Korea is an important strategic asset for China. There is no way that China is going to allow unification under the South Korean auspices," he said.

In fact, a majority of South Koreans see China as not only a key player in a reunification process but also a major obstacle, showed recent opinion polls.

Speaking after Mearsheimer, a Chinese scholar refuted the view.

Wang Jisi, president of the Institute of the International and Strategic Studies at Peking University. said China is "not a dominant factor" in Korea's unification, adding the two Koreas hold the key.

"The stability of the DPRK (North Korea) is in our best interests," he said in English, adding China believes the U.S. is also to blame for tensions in the region.

"Owing to China's increased distrust of U.S. intentions in the region, it sees the tensions on the Korean Peninsula as caused by both Pyongyang and Washington," he said. "The Chinese expect Seoul to be more 'neutral' between the U.S. and China. The U.S. also has to accommodate the rise of China."

Above all, China does not want the U.S. to interfere with other countries' affairs, he stressed.

In his opening speech at the conference, South Korea's top diplomat agreed that diplomatic challenges facing South Korea include seeking sustainable peace and cooperation in Northeast Asia.

"Certainly, bilateral relations between regional countries are the primary factor in this mission. Above all, U.S.-China relations are a crucial factor," Foreign Minister Yun Byung-se said.

He reiterated that Seoul's relations with Washington and Beijing are not a "zero-sum" game.

"Here, we can see elements of both competition and cooperation, so it is critical that we do not fall into the trap of a zero-sum or preordained mindset," he said.

With the title "Opening the next chapter: where Korean diplomacy stands," the event marks the 70th anniversary of the end of World War II and Korea's liberation from Japan's 35-year colonial rule. (Yonhap)