Even as they pledged to build "a new model" of relations, President Obama and President Xi Jinping of China ended two days of informal meetings here on Saturday moving closer on pressuring a nuclear North Korea and addressing climate change, but remaining sharply divided over cyberespionage and other issues that have divided the countries for years.
Although the leaders of the world's two biggest powers made no public statements on their second day of talks, their disagreements — over cyberattacks as well as arms sales to Taiwan, maritime territorial disputes in the South China Sea and manipulation of the Chinese currency — spilled into the open when senior officials from both countries emerged to describe the meetings in detail.
From the outset, the White House said the purpose of the meetings here was not to announce new deals or understandings — "deliverables," in diplomatic parlance — but to create a more comfortable relationship between Mr. Obama and Mr. Xi, who took full power in March, that could avoid plunging the two nations into escalating conflict.
(Read More: Pentagon: Chinese Government Launching Cyberattacks)
Even so, the White House announced that the two countries had reached at least one concrete accord that environmentalists welcomed as a potential step in combating climate change. China and the United States agreed to discuss ways to reduce emissions of hydrofluorocarbons, known as HFCs, that are used in refrigerants and insulating foams.
Representative Henry A. Waxman of California, one of several senior Democrats who urged Mr. Obama to raise the issue in these talks, praised the announcement. "A global phase-down of HFCs would eliminate more heat-trapping gases by 2050 than the United States emits in an entire decade," he said in a statement.
Mr. Obama and Mr. Xi also found areas of agreement over North Korea, which under pressure from China has muted a flurry of belligerent statements after nuclear and missile tests this year. After suspending nearly all contact with South Korea, the North has in recent weeks reversed course, and on Sunday officials of the two countries are to meet at a border village to arrange the first cabinet minister-level meeting in six years.
Mr. Obama's administration has welcomed China's new assertiveness with its neighbor and ally, believing that it reflects a new calculation that a constant state of crisis on the Korean Peninsula is destabilizing for the Chinese as well. The two presidents held a long discussion on North Korea over what Tom Donilon, Mr. Obama's departing national security adviser, called "a very lively dinner" on Friday, and he said that they agreed that dealing with the country's nuclear arsenal was a promising arena for "enhanced cooperation."
"They agreed that North Korea has to denuclearize, that neither country will accept North Korea as a nuclear-armed state" and that their two nations would work together to achieve that through pressure on Pyongyang, Mr. Donilon said.
(Read More: Hard Issues On Table at Obama, Xi 'Informal' Summit)
The two presidents met for nearly eight hours beginning Friday evening, and appeared eager to redefine the relationship in a way that would allow their countries to overcome their economic, political and diplomatic differences, rather than letting new — or old — crises derail progress across the spectrum of issues.
On the most contentious issue in recent months — American accusations that Chinese corporations linked to the military had pilfered military and economic secrets and property in cyberspace — the officials seemed to speak past each other. That dominated Saturday's talks here at a secluded estate, but ended without a clear acknowledgment by Mr. Xi of any culpability.
China's state councilor, Yang Jiechi, said China strongly opposed hacking and cyberespionage and was itself a victim, while Mr. Donilon warned that the threat from China threatened to constrain the spirit of partnership Mr. Obama and Mr. Xi publicly declared they wanted.
Mr. Obama warned that if the hacking continued, Mr. Donilon said, it "was going to be a very difficult problem in the economic relationship."
In remarks during a joint appearance on Friday night, Mr. Obama at least publicly softened his language and spread the blame for the hacking and theft of business, financial and military information. "Those are not issues that are unique to the U.S.-China relationship," the president said. "Those are issues that are of international concern. Oftentimes it's nonstate actors who are engaging in these issues as well."
He added, "We're going to have to work very hard to build a system of defenses and protections, both in the private sector and in the public sector, even as we negotiate with other countries around setting up common rules of the road." And, Mr. Obama said, China would face similar threats as its economy develops — Mr. Xi suggested it already had — "which is why I believe we can work together on this rather than at cross-purposes."
(Read Op-Ed: Shelve Diplomacy, Mr. President: Get Tough on China)
Secretary of State John Kerry, who attended the meetings, has previously announced that the two countries would discuss the matter as part of the annual meetings known as the Strategic and Economic Dialogue, to be held in Washington in July.
Mr. Yang said that the two discussed a host of contentious issues and "did not shy away from differences." Mr. Xi called on the United States to end its arms sales to Taiwan, he said, and reasserted its territorial claims, while pledging to resolve them peacefully. Mr. Yang also defended China's control of its currency and said it was not the core trade issue between them.
Broadly, though, both leaders urged cooperation, not conflict. Mr. Obama called for joint efforts to address climate change, including through sharing clean-energy technologies, and to establish better military communications so "that we each understand our strategic objectives at the military as well as the political levels."
'We Can Work Together on This'
Mr. Xi agreed. "China and the United States must find a new path," he said, "one that is different from the inevitable confrontation and conflict between the major countries of the past."
The Chinese president, who as a young man lived for a time with a family in Iowa and visited again during a trip to the United States last year as vice president, said he and Mr. Obama would keep "close communication" through letters, phone calls, bilateral meetings and visits, adding, "I invited President Obama to come to China at an appropriate time for a similar meeting like this."
"Both sides have the political will to build this relationship," Mr. Xi said.
For all the advance talk of the informality of the meetings, they largely followed well-established diplomatic routine, and the necessary translations limited spontaneity. The two leaders sat opposite each other at a conference table, flanked by their senior aides and interpreters. When they appeared before journalists, briefly, they selected one American and one Chinese reporter to ask a question each. According to White House officials, they then continued their discussion until 10:44 p.m. over a dinner that lasted almost two hours — including lobster tamales, porterhouse steak and cherry pie, prepared on site by the celebrity chef Bobby Flay.
Mr. Obama stayed overnight at the Sunnylands retreat, a 25,000-square-foot Modernist mansion that was the winter oasis of the billionaire publisher and Republican patron Walter H. Annenberg, but the Chinese party chose to stay at a nearby hotel.
After breakfast on Saturday, the two presidents resumed discussions. They emerged first from the main house at Sunnylands and strolled across a bucolic expanse of grass and over a pedestrian bridge with the San Jacinto Mountains as a spectacular backdrop. Wearing shirts open at the neck and no jackets, they were accompanied only by their interpreters, and their discussion could not be discerned.
While their talks on Friday evening delved into security and geopolitical issues, the meetings on Saturday focused on economic and trade issues.
Mr. Obama, Mr. Xi and their all-male attendants forsook ties, which was just as well, since the room at the Annenberg estate where they met seemed uncomfortably hot at times. But perhaps understandably, given the personalities of both leaders, there was little sign of backslapping bonhomie in what administration officials had advertised as an "unscripted" setting.
After the talks ended on Saturday, Mr. Obama and Mr. Xi had tea with Mr. Xi's wife, Peng Liyuan, a famed singer and major general, and Madame Ni, the wife of the Chinese ambassador to the United Nations. The Chinese delegation left the retreat about noon. For Mr. Xi, it ended a trip that last week had him in Trinidad and Tobago, Costa Rica and Mexico — another sign of Beijing's global ambitions and search for new energy sources.
Mr. Obama planned to stay another night at Sunnylands. After Mr. Xi's departure, he golfed on the estate's nine-hole course — one Republican presidents since Dwight D. Eisenhower have played — with three friends from his high-school days in Hawaii, despite temperatures exceeding 100 degrees.