The first phone call between South Korean President Park Geun-hye and Chinese President Xi Jinping since the North's nuclear test appears to show that Beijing is still unprepared to act differently in its handling of Pyongyang, a U.S. expert said.

In the 45-minute call initiated by Xi, Park asked for Chinese cooperation in efforts to put together U.N. sanctions strong and effective enough to make North Korea change its course, saying North Korea's provocations pose threats to peace in Northeast Asia and the world.

But Xi repeated China's existing positions that the Korean Peninsula should be free of nuclear weapons and all relevant parties should deal with the situation in a "cool-headed" manner and stick to the principle of dialogue and negotiations to resolve problems.

"It was President Park who specifically raised the nuclear issue. Xi Jinping did not," Jonathan Pollack, a senior fellow at the Brookings Institution, told Yonhap News Agency by phone. "What I think Xi is saying is 'Let's continue with all of our developing relations economically and in other areas of broader cooperation,' but he seemed unprepared to think about this in larger strategic terms."

The phone conversation came amid mounting calls for China to use more of its leverage with Pyongyang to rein in the recalcitrant neighbor. Chinese cooperation is key to putting together strong sanctions as Beijing is a veto-wielding permanent member of the U.N. Security Council and the main provider of food and fuel for the North.

But China has balked at calls for a tough response.

Pollack pointed out how much effort Park has put in to strengthen relations with China and build personal ties with Xi, including her attendance at a massive Chinese military parade in September that was shunned by Western leaders.

"President Park's expectation, I think legitimate expectation, was that she wanted a different answer from China. She's made a lot of commitment to China," the expert said, noting that Park risked domestic and international criticism to attend the September parade.

"She expected something in return, and so far, she has not received that," he said.

Xi later held a phone conversation with U.S. President Barack Obama.

The White House said the two leaders agreed on the importance of a "strong and united international response" to North Korea's nuclear test and its planned rocket launch and that they will not accept North Korea as a nuclear weapons state.

But according to China's Xinhua news agency, Xi insisted on a solution through dialogue and consultation, calling the current situation complicated and sensitive and saying that China is committed to the goal of denuclearization of the peninsula.

Beijing has condemned the North's nuclear test, but has been lukewarm about calls for stern responses. Analysts have long said Beijing fears that pushing Pyongyang too hard could lead to its collapse, instability on its border with China and the ultimate emergence of a pro-U.S. nation.

"If you're sitting in Pyongyang, if you look at what China has said and has not been prepared to do, then Kim Jong-un probably feels more relaxed because in effect he knows or thinks that China's words are empty words and it does not want to impose any cost on them," Pollack said.

"My argument is that unless and until Kim Jong-un becomes convinced that there is a cost, either political, economic or otherwise, to be paid for its continued testing programs, both nuclear weapons and missiles, he has no incentives to do things differently," he said.

Unless there are "teeth" to China's criticism, then Pyongyang would draw the conclusion that China is not prepared to take serious additional steps to rein in North Korean behavior, he said.

The expert also said that the North Korea problem is a "test case" in relations between the U.S. and China, including whether China can fulfill U.S. expectations "on a matter which both governments claim is definitely a shared interest."

"So far the answer is no," he said. "And the ball is really in China's court now to act differently regardless of the words it uses." (Yonhap)