South Korean President Park Geun-hye left for Beijing on Thursday for her first summit with Chinese President Xi Jinping that will be watched closely as to how far China would go in committing itself to helping end North Korea's nuclear program.

It is Park's second overseas trip since taking office in late February. In May, she visited the United States and held summit talks with President Barack Obama. The four-day trip to China also includes a stop in the ancient western city of Xian later this week.

The centerpiece of the visit will be the summit with Xi, set for later Thursday, where the two leaders are expected to focus on the international standoff over North Korea's nuclear programs and ways to enhance bilateral economic and other cooperation.

The meeting comes as China has been taking an unusually tough stance on Pyongyang after the provocative regime pressed ahead with a long-range rocket launch in December and its third nuclear test in February in defiance of China's appeals.

Early this month, Xi agreed at a summit with Obama that North Korea will never be recognized as a nuclear weapons state and should abandon its nuclear weapons aspirations, an unusually blunt stance, given Beijing's traditional embrace of Pyongyang.

Park has repeatedly said that she is looking to use the planned meeting with Xi to enlist the help of North Korea's most important ally in pressuring Pyongyang to give up its nuclear programs and become a responsible member of the international community.

Hopes have since risen that China could express a firmer commitment to ending Pyongyang's nuclear program during Park's visit. News reports have said the two sides plan to issue a joint communique, where they are expected to pledge to work together in helping induce Pyongyang's denuclearization.

"The North Korean nuclear issue is not easy," a presidential official said. "But what is for sure is that there will be fairly in-depth discussions ... There will be good discussions as the two countries share the common goal of resolving the North Korean nuclear issue."

As a key provider of economic aid and diplomatic protection for North Korea, China has long been considered the only country with any meaningful influence over Pyongyang, though it has been reluctant to use that leverage over concern that pushing the North too hard could hurt its national interests.

But some analysts say that China could be shifting its policy focus on Pyongyang as the prospect of a nuclear North Korea has become a valid concern following February's atomic test. They say Beijing may be concerned that Pyongyang's nuclear armament could give rival Japan a pretext for building up its military power and spark a regional arms race.

Since the February nuclear test, China has backed a U.N.

sanctions resolution against the North and has been carrying out the restrictions more vigorously than before. Beijing even joined in separate American sanctions by suspending all transactions with the North's Foreign Trade Bank, which was accused of financing Pyongyang's nuclear programs.

But others say China's recent toughness does not represent any fundamental change in policy.

They say China still places top priority on keeping Pyongyang alive because instability in the neighboring nation could hurt its economic growth, trigger a massive influx of refugees and leading to the emergence of a unified Korean Peninsula under South Korean and U.S. control across its border.

North Korea has recently been making a series of dialogue proposals after months of ratcheting up tensions with bellicose rhetoric, including threats to launch nuclear strikes against South Korea and the U.S.

The widespread view is that China's pressure is behind Pyongyang's overtures.

Earlier this month, Pyongyang proposed to hold senior-level talks with the U.S. Washington reacted negatively to the offer, saying Pyongyang should first take steps demonstrating its seriousness about dialogue.

Park has also voiced opposition to holding talks with the North for the sake of talks. She has also called strongly for breaking what she dubs the "vicious cycle" of North Korea winning economic and other concessions repeatedly through provocations.

Bilateral issues are also expected to be discussed at Park's summit with Xi, such as ongoing negotiations to free up trade between two of Asia's biggest economies, as the neighboring countries try to chart a new course for expanding all-round cooperation.

Seoul and Beijing launched official negotiations in May last year to tear down barriers in trade between the two countries. So far, the sides have held five rounds of talks, and a sixth round is scheduled for early July.

On Friday, Park plans to meet one-on-one with two other top Chinese leaders, Premier Li Keqiang and Zhang Dejiang, chairman of the Standing Committee of the National People's Congress, to talk about ways to strengthen relations between the two countries, officials said.

Her three-day visit to Beijing also includes an address at a forum of business leaders of the two countries, a speech at a university in Beijing and a tour of South Korean firms operating in China.

Park is expected to deliver at least part of the university speech in Chinese.

On Saturday, Park flies to the western Chinese city of Xian.

Xian, an ancient capital with more than 3,000 years of history, is a base for China's push to develop western parts of the country and has great potential for economic cooperation as the city could serve as a foothold for South Korean firms trying to expand to Central Asia and Europe.

While there, Park plans to meet with leaders of the Shaanxi province for discussions on ways to increase economic cooperation and other ties between the two sides. She also plans to visit South Korean companies and cultural sites there, officials said.

A record 71 business leaders will accompany Park on the Chinese trip. The number is much larger than the 36 in 2008 when then President Lee Myung-bak visited China, and the 51 in May when Park visited the United States. (Yonhap News)