BEIJING — An upcoming summit with President Barack Obama comes at a "critical juncture" in relations between China and the U.S., Chinese President Xi Jinping said Monday, underscoring the challenge they face in confronting divisive security issues and overcoming growing distrust.

Xi told U.S. National Security Adviser Tom Donilon – who was in Beijing to prepare for the June 7-8 meeting – that he expected positive results from the talks, which will be their first face-to-face meeting since Obama's re-election and Xi's promotion to head of the Communist Party last November.

"The current China-U.S. relationship is at a critical juncture," Xi said. The sides must now "build on past successes and open up new dimensions for the future."

In a sign that both sides want to stem a drift in ties, the summit is taking place months earlier than the two presidents were supposed to meet. The setting – at the private Sunnylands estate of the late publishing tycoon Walter Annenberg in southern California – is supposed to be informal, giving Xi and Obama a chance to build a rapport.

Donilon flew to Beijing this week to prepare an agenda and straighten out other technical issues. He told Xi that Obama is "firmly committed to building a relationship defined by higher levels of practical cooperation and greater levels of trust, while managing whatever differences and disagreements might arise between us."

Meeting earlier with State Councilor Yang Jiechi, China's senior foreign policy official, Donilon said the summit is a chance for the two presidents to work through problems. Though they did not identify those challenges in their public remarks, ties are strained across the board, from longstanding differences over the Iranian and North Korean nuclear programs to new disputes over cyberattacks and China's more assertive pursuit of territorial claims against U.S. allies Japan and the Philippines.

"The meeting will be an important opportunity for our presidents to have in-depth discussions about U.S.-China relations, and a wide range of global and regional challenges facing both our countries," Donilon said.

That Xi agreed to an informal summit has been seen by Chinese and U.S. experts as positive. His predecessors always preferred formal state visits, splashing images of White House ceremonies and banquets in the Chinese media to bolster their standing as world statesmen.

Good will aside, distrust has deepened in relations in recent years as the U.S. feels its world leadership challenged and China, its power growing, demands greater deference to its interests and a larger say over global rule setting. Chinese officials and state media regularly say Washington is thwarting China's rise, strengthening alliances in Asia to hem in Beijing and discouraging Chinese investment in the U.S. on grounds of national security.

The official Xinhua News Agency reported Monday that ships and submarines from the Chinese navy's three fleets staged drills in the South China Sea late last week. The area is already a flashpoint, with Beijing's aggressive claims to disputed islands having rattled the Philippines, Vietnam, Malaysia and Brunei.

On Sunday, Li Keqiang – on a visit to Germany in his first trip abroad as China's premier – pressed China's claim to a cluster of East China Sea islands held by Japan. Traveling to Potsdam, where allied powers declared the terms for Japan's surrender 68 years ago in the waning days of World War II, Li told reporters that Japan must not "deny or glorify the history of fascist aggression."

The aggrieved sense emanating from Beijing goes beyond recent flare-ups in old territorial disputes. The website of the People's Daily, the Communist Party's flagship newspaper, is running a recurring column that takes a critical look at Americans and their institutions. First called "Immoral, dishonest Americans," the title of the column was changed to "The Americans you don't know about."

One item on Donilon's summit plans is the guest list. Xi will stop in California after formal visits to Trinidad and Tobago and Mexico where he will be accompanied by a large group of senior officials. If that entourage descends in full on the Sunnylands estate, U.S. diplomats said the White House might feel the need to bring similarly large numbers, making the summit less intimate.

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  • In this Sunday March 10, 2013 photo, soldiers dressed as ushers guard front row seats on the second floor of the main hall of the Great Hall of the People, while a live video image of Xi Jinping, the Chinese Communist Party's General Secretary and the nation's incoming-President, is shown on a screen during a plenary session of the National People's Congress, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Sunday, March 10, 2013 photo, delegates from the Chinese People's Liberation Army march in formation into the Great Hall of the People to attend a plenary session of the National People's Congress, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Tuesday, March 5, 2013 photo, a police car drives past while paramilitary policemen in uniforms and in plainclothes keep watch on people who gathered to see a flag-raising ceremony at dawn at Tiananmen Square before the opening session of the annual National People's Congress that is to be held later in the morning inside the nearby Great Hall of the People, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Sunday, March 10, 2013 photo, a monk, who is also a delegate, holds a cup of tea while looking for an unoccupied chair outside the main hall of the Great Hall of the People, where a plenary session of the National People's Congress is being held, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Sunday, March 10, 2013 photo, delegates sip tea, chat, rest, and take photos outside the main hall of the Great Hall of the People, where a plenary session of the National People's Congress is being held, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Sunday, March 10, 2013 photo, a delegate takes a nap while other delegates chat and drink tea outside the main hall of the Great Hall of the People, where a plenary session of the National People's Congress is being held, in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, delegates of the National People's Congress chat, use a mobile phone, and give an interview in a corridor at the Great Hall of the People in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, National People's Congress delegates from eastern China's Fujian province attend a group discussion, with top provincial leaders seated in the center, at Fujian Hall inside the Great Hall of the People in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, soldiers dressed as ushers guard a corridor that leads to halls where closed-door meetings of the National People's Congress delegations are held, while an anti-explosive device, left, and a vase, right, are placed nearby, inside the Great Hall of the People in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, National People's Congress delegates, one dressed in ethnic attire, walk past a glass screen to join a group discussion of delegates from central China's Hunan province at Hunan Hall inside the Great Hall of the People in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, top regional officials, who are also delegates, shake hands while other National People's Congress delegates from northern China's Inner Mongolia region wait for a group discussion to begin at the Inner Mongolia Hall inside the Great Hall of the People in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Thursday, March 7, 2013 photo, soldiers dressed as ushers guard corridors, stairways, and elevators while a delegate, second from right, walks past them inside the Great Hall of the People, where delegates of the National People's Congress are holding group discussions in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Tuesday, March 5, 2013 photo, delegates from the People's Liberation Army walk up steps to enter the Great Hall of the People to attend an opening session of the National People's Congress on a hazy day in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Monday, March 4, 2013 photo, a soldier dressed as an usher, front, stands guard at the Great Hall of the People, while delegates, one of them wearing an ethic outfit, walk up the steps to attend a session of the National People's Congress in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Monday, March 4, 2013 photo, ethnic minority delegates wearing traditional attire march to the Great Hall of the People to attend a session of the National People's Congress in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Tuesday, March 5, 2013 photo, a delegate, right, enters the main hall of the Great Hall of the People while soldiers dressed as ushers guard the entrances during the opening session of the National People's Congress in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Tuesday, March 5, 2013 photo, a delegate leaves the main hall of the Great Hall of the People while other delegates of the Chinese People's Political Consultative Conference read copies of a government work report during the opening session of the National People's Congress in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Tuesday, March 5, 2013 photo, delegates leave the Great Hall of the People after an opening session of the National People's Congress in Beijing, China. (AP Photo/Alexander F. Yuan)

  • In this Sunday, March 3, 2013 photo, journalists wander in front of an electronic screen that is showing slogans as part of a Chinese Communist Party's propaganda video at Tiananmen Square, while the opening session of the Chinese People's Political Consultative Conference is held in the nearby Great Hall of the People in Beijing, China. The slogan reads "To deepen the study and implementation of the spirit of the Communist Party's 18th National Congress." (AP Photo/Alexander F. Yuan)