The US and China pledged to work together to combat the "twin challenges" of climate change and air pollution, the countries announced on Saturday after US Secretary of State John Kerry left Beijing.

"In light of the overwhelming scientific consensus on climate change and its worsening impacts, and the related issue of air pollution from burning fossil fuels, the United States and China recognize the urgent need for action to meet these twin challenges," the two countries said in a joint statement, released after Kerry's two-day trip to China.

Under the collaboration, the US and China will share information on their respective post-2020 plans to limit greenhouse gas emissions, and the two countries will "commit to devote significant effort and resources to secure concrete results" by the Sixth US-China Strategic and Economic Dialogue taking place later this summer.

"Now make no mistake: this is real progress," Kerry said after he arrived in Jakarta, Indonesia from Beijing. "The US and China are the world's two largest economies. We are two of the largest consumers of energy, and we are two of the largest emitters of global greenhouse gases - together we account for roughly 40 percent of the world's emissions."

The countries' talks on climate change came during Kerry's Asian tour, during which he visited China, South Korea, and Indonesia before going to Abu Dhabi.

On Friday, Beijing urged Washington to respect historical facts and not take sides on territorial disputes in the East China Sea and South China Sea, as Kerry met Chinese leaders.

Foreign Minister Wang Yi told Kerry that Beijing is committed to peacefully settling the disputes through consultations.

"However, nobody can shake our determination in safeguarding national sovereignty and territorial integrity," Wang said. "We hope the United States will respect historical facts and China's sovereign interests, view relevant issues objectively and fairly, and not take sides." He urged Washington to take steps to maintain regional stability.

President Xi Jinping, Premier Li Keqiang and State Councilor Yang Jiechi also met Kerry on Friday.

Li noted that next year marks the 70th anniversary of victory in the world anti-fascist war. "We can prevent a repeat of the war only by facing and learning from history," Li said.

Kerry assured Chinese officials and leaders that the US does not intend to contain China, and that China matters greatly to the US.

The remarks came a day after Kerry said on Thursday in Seoul, the first leg of his Asia trip, that China's Diaoyu Islands fall under the security treaty that obliges the US to intervene on Japan's behalf if it is attacked by a third country.

"That is the position of the United States with respect to those islands," he said, referring to the islands by their Japanese name.

Kerry is on his fifth trip to Asia since taking office last year. The Feb 13 to 18 tour will also take him to Indonesia and the United Arab Emirates.

Japan's relations with China and South Korea deteriorated further in December after Japanese Prime Minister Shinzo Abe visited the Yasukuni Shrine, which honors Japanese war dead, including 14 Class-A war criminals.

But Kerry said on Thursday that while there is "legitimate concern about the past," there are also "issues of enormous current pressing concern that deal with security that are relevant in terms of today, not in terms of history.

"And it is vital for us to be able to continue to stay focused on the high stakes, in terms of everybody's lives right now," he said.

Such remarks have irritated the media and public in South Korea, another ally of the US. South Korea's Yonhap News Agency said in a commentary on Friday that Kerry put the two issues of security and history in the wrong order.

Hong Moon-jong, secretary-general of South Korea's ruling Saenuri Party, criticized Kerry for his lack of understanding of history. "It would be inappropriate to treat the perpetrators on the same footing as victims," Hong said.

Xinhua News Agency said in a commentary on Friday, "To ease flaring regional tensions, what Washington is expected to do right at the moment is not to blame China but ask Japan to call off its provocative moves."

Douglas Paal, vice-president for studies at the Carnegie Endowment for International Peace, said, "Abe is trending toward taking a view of history significantly at odds with the American view, and that should be voiced."

Sun Zhe, director of the Center for US-China Relations at Tsinghua University, said Washington has showed its support for Tokyo through its deeds. For example, the US may have criticized Abe's visit to the Yasukuni Shrine, but only once. In addition, the US government has referred to China's Diaoyu Islands by their Japanese name.

However, Sun said Kerry's arrival showed the great importance Washington attaches to its relations with Beijing.

Jia Xiudong, a senior researcher on international affairs at the China Institute of International Studies, said that despite Beijing's dissatisfaction with the way Washington is handling China-Japan issues, Kerry is actually in China to prepare for frequent bilateral high-level meetings this year.

"But the US should show its sincerity and take concrete steps to establish a new type of relationship between major powers," Jia said.

Kerry also exchanged views with Chinese officials on Friday on the denuclearization of the Korean Peninsula. "We will never allow any chaos or war on the peninsula," Wang Yi told Kerry.

Zhang Fan in Beijing contributed to this story.

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