President Obama and Chinese President Xi Jinping walked the grounds of the Sunnylands estate Saturday in Rancho Mirage, Calif., for a highly unusual one-on-one talk. The talk and the dress code were just about the only informal parts of the “informal” summit. (Evan Vucci/AP)

It was orchestrated as the shirt-sleeves summit, where President Obama, embarking on his second term with a strategic focus on Asia, and Chinese President Xi Jinping, starting his first year of a decade-long rule, might cool tensions between their rival nations and forge a comfortable friendship.

But even before the leaders arrived for two days of high-stakes meetings here, some suspicions abounded. Xi and his delegation declined to stay at Sunnylands, the expansive desert estate hosting the summit, believing that it might be bugged by the Americans. Instead, the Chinese checked into a nearby hotel.

Once the meetings began Friday, Obama and Xi’s conversations were often stilted. Neither speaks the other’s language fluently, and they opted against the simultaneous translation often used in such instances, so their statements were interrupted every couple of sentences by interpreters. This slowed down the talks and prevented spontaneous back-and-forth.

Despite all the buzz about dispensing with diplomatic formalities at Sunnylands, rigid customs were mostly maintained. Most of the talks occurred at a long table where Obama and Xi each were flanked by an interpreter and six advisers, with note-takers from each country sitting in the corner.

One of the few signs of informality was the dress code: Everyone, and they were all men, wore suit jackets and white dress shirts, but no neckties.

Yet for the Chinese — whose engagements with the United States historically have been formal, sometimes stifling, and dictated by diplomatic talking points — agreeing to come to Sunnylands at all, free as it was of the ceremonial trappings of state visits to Washington, was considered an unusual gesture.

“The president had very good discussions in an informal atmosphere — uniquely informal atmosphere — with President Xi,” said Thomas E. Donilon, Obama’s national security adviser, who negotiated with the Chinese over planning the summit and participated in the meetings.

“If you go back through studying each of the encounters between an American president and the leadership of China since President Nixon’s historic meeting in February of 1972 in China, I think the uniqueness and the importance of a number of aspects of this encounter really come to the fore,” Donilon told reporters.

Obama has a few things in common with Xi. They both spent time in rural Iowa — Obama as a presidential candidate and Xi as a young provincial officer researching agriculture — and Xi has enrolled his daughter at Harvard University, where Obama studied law.

U.S. officials had hoped that the relaxed setting of this Rancho Mirage retreat — built at the intersection of Bob Hope and Frank Sinatra drives as a winter getaway by the late billionaires Walter and Leonore Annenberg — might nurture trust.

On Saturday morning, Obama and Xi spent about 50 minutes talking one on one, something China experts called an extraordinary occurrence. They took a leisurely stroll around the landscaped grounds, past an artificial pond and over a bridge, and retired in the shade on a bench that Obama had custom-built from a California redwood tree as a gift for Xi.

Obama and Xi were aided by interpreters but spoke out of earshot of their advisers — a significant break with tradition.

“It’s generally not how they roll,” said Christopher Johnson, a former China analyst for the CIA who now is a senior adviser at the nonpartisan Center for Strategic and International Studies. “Their system is one where everything is a collective leadership.”

Johnson painted a contrast with Xi’s predecessor: “With Hu Jintao, he had minders to make sure the boss didn’t go off the mutually agreed script.”

Johnson, observing their body language during the walk, said Obama and Xi showed “mutual deference” and “were comfortable in their own skin.”

Still, Obama appeared more laid-back than his Chinese counterpart, wearing his shirt sleeves rolled up while Xi kept his buttoned down.

When Obama and Xi rejoined their delegations inside, though, the talks grew tense. That’s when Obama confronted Xi about China’s cybertheft and warned him that continued activity would threaten economic ties between the two nations, Donilon said.

The night before, around 9 p.m., the presidents and their delegations sat for dinner at a table set with fine china and flowers. Bobby Flay, the celebrity chef, flew in at Obama’s invitation — and on Flay’s own dime, a White House official said — to prepare a meal of lobster tamales, porterhouse steak and cherry pie.

Between bites Friday evening, Obama and Xi reached an accord to work together to apply pressure to halt North Korea’s nuclear arms development, Donilon said.

The two presidents’ appearances before reporters were meticulously choreographed, as is the norm for bilateral meetings.

First, an initial handshake against the backdrop of the stunning San Jacinto Mountains. Second, after the leaders privately discussed their domestic and foreign policy priorities, another photo op. They made brief statements declaring their hopes: Obama promised “a new model of cooperation,” while Xi vowed to “chart the future of China-U.S. relations.”

Finally, they took questions from reporters, agreeing to only one from each nation’s press corps. Obama called on an Associated Press reporter, who raised hacking, the most contentious issue on the summit agenda. She asked Xi whether he acknowledged in his talks with Obama that China has launched cyberattacks against the United States. Xi did not directly answer but said that China, too, has been a victim of such attacks.

Then Xi called on a reporter from China Central Television, who threw him a relative softball, asking whether Xi and Obama had reached areas of consensus toward building “a new model of major country relationship.”Back at the press filing center, where audio of the question was streaming, some Japanese and U.S. reporters laughed.

“The Chinese dream is about cooperation, development, peace and win-win,” Xi said. “And it is connected to the American dream and the beautiful dreams people in other countries may have.”

That was the last time Obama and Xi were supposed to speak in public. The next morning, during their Saturday stroll, a U.S. reporter shouted a question about how the talks were going.

“Terrific,” Obama replied. But Xi, sticking to the script, stayed silent and smiled.