President Barack Obama and President Xi Jinping wrapped up their first U.S.-China summit Saturday after securing new levels of understanding on North Korea, climate and cyber issues.

Obama and Xi spent a total of eight hours together over two days, encompassing talks, a private dinner, and a stroll through the lush vegetation of a California desert oasis, seeking to forge a personal connection.

U.S. officials said the unusually informal talks at the Sunnylands retreat, had allowed Xi and Obama a rare chance to swap insights about where they hoped to lead their own nations, and the world in years to come.

U.S. National Security Advisor said Obama and Xi had closely consulted on North Korea's recent nuclear brinkmanship, and agreed that they would work together on the "denuclearization" of the Korean peninsula.

The two men achieved "quite a bit of alignment" on the issue, Donilon said, and praised recent steps taken by Beijing to expresses disapproval of the nuclear and missile tests and bellicose rhetoric of its nominal ally.

Obama meanwhile made clear that a rash of suspected Chinese cyber attacks on U.S. commercial property and military technology would be an "inhibitor" to relations, and would be a "very difficult" problem to solve.

Donilon said that Xi "acknowledged" how important the issue was to Washington, and left California in no doubt where Obama stood.

The leaders also offered directions to working group officials from both sides who are due to sit down to discuss cyber issues in July.

On Friday, Obama called for common "rules of the road" on cybersecurity.

"It's critical, as two of the largest economies and military powers of the world, that China and the United States arrive at a firm understanding," Obama said.

Xi said he wanted "good-faith cooperation" to clear up "misgivings" by the United States about cybersecurity, telling reporters that China was also "a victim of cyberattacks."

In a more tangible outcome from the talks at the Sunnylands retreat, the White House said Obama and Xi had agreed on a joint effort to combat climate change, specifically the production of hydroflourocarbons or "super greenhouse gases."

"A global phase down of HFCs could potentially reduce some 90 gigatons of

CO2 equivalent by 2050, equal to roughly two years' worth of current global greenhouse gas emissions," a White House statement said.

The gases are used in air conditioners and refrigerators.

China -- by far the largest producer of HFCs -- had until recently resisted efforts by the United States and other wealthy nations to scale back emissions of the gases, arguing that alternatives in appliances were not fully ready.

But it agreed in April to end HFC production by 2030 as part of a $385 million assistance package by wealthy countries under the Montreal Protocol, which was set up to fight the depletion of the ozone layer.

Xi is expected to lead China during a decade in which it will overtake the United States as the world's largest economy.

Hovering over the summit at a resort once frequented by Frank Sinatra and Richard Nixon was a vexing question for both countries -- whether China's rise in Asia and in the world means an inevitable clash with the United States.

In their first meeting since Xi assumed power from ex-president Hu Jintao in March, Obama expressed the hope for a "new model of cooperation between countries based on mutual interest and mutual respect."

"It is in the United States' interests that China continues on the path of success because we believe that a peaceful and stable and prosperous China is not only good for the Chinese, but also good for the world and the United States."

Xi invited Obama to pay a return informal visit to China. Donilon said the two sides would work together to set a date, and also to work out a schedule for an exchange of state visits.

Mirroring his host's theme of a new approach, Xi said on Friday that "the vast Pacific Ocean has enough space for two large countries like the United States and China."

Xi also reiterated his frequent, if occasionally vague call for world powers to think differently about relations.

"We need to think creatively and act energetically, so that, working together, we can build a new model of major country relationship," Xi said.

The two leaders had not been expected to meet until the G20 summit in Russia in September. But both sides, sensing uncertainty seeping into a complicated and often difficult relationship, saw value in an earlier encounter.
(AFP)