Talks between US Secretary of State Hillary Clinton and Chinese leaders have failed to narrow gaps on how to end the crisis in Syria and resolve Beijing's territorial disputes with its smaller neighbours over the South China Sea.
Mrs Clinton, who met president Hu Jintao and foreign minister Yang Jiechi, wants China to stop backing the regime of Syrian president Bashar Assad, and has been pushing for the country to be more flexible in lowering tensions over the oil-rich South China Seas.
But comments from Mrs Clinton and Mr Yang showed that the two countries remain divided on those issues, although both said they were committed to working together.
The US and other countries are upset that China and Russia have repeatedly used their veto powers in the UN Security Council to block actions that could have led to sanctions against Mr Assad's regime.
China says Syria's civil war needs to be resolved through negotiations and not outside pressure.
"I think history will judge that China's position on the Syria question is a promotion of the appropriate handling of the situation, for what we have in mind is the interests of the people of Syria and the region," Mr Yang said at a news conference given with Clinton.
Mrs Clinton responded by saying the violence was boiling over into other countries and that strong backing should be given to the Security Council.
"It is no secret that we have been disappointed by Russia and China's actions blocking tougher UN Security Council resolutions and we hope to continue to unite behind a real path forward to end the violence in Syria," she said.
Mrs Clinton had also been scheduled to meet vice president Xi Jinping, who takes over as China's top leader later this year, but that was cancelled.
"The Chinese side has cited unexpected scheduling reasons for the cancellation of the Secretary's meeting with Vice President Xi," said a senior US state department official, speaking on condition of anonymity.
A meeting between Mr Xi and the visiting prime minister of Singapore, Lee Hsien Loong, also was cancelled without explanation. Mr Yang would say only there should not be "unnecessary speculation".
Before meeting Mr Hu, Mrs Clinton said the US-China relationship is strong. "We are able to explore areas of agreement and disagreement in a very open manner, which I think demonstrates the maturity of the relationship and the chance to take it further in the future," she said.
Mrs Clinton arrived in China from Indonesia, where she urged south-east Asian nations to present a unified front in dealing with China in attempts to ease rising tensions in the South China Sea.
China and a host of south-east Asian countries, including the Philippines, Vietnam and Brunei, have overlapping claims to several small but potentially energy-rich areas of sea.
The US wants China and the other claimants to adopt a binding code of conduct for the region, along with a process to resolve maritime disputes without coercion, intimidation or the use of force.
Clinton wants the Chinese to drop their insistence on settling conflicting claims with individual nations and instead embrace a multilateral mechanism that will give the smaller members of the Association of South East Asian Nations greater clout in negotiations.
Mrs Clinton wants all parties to make meaningful progress by a November summit of East Asian leaders that US president Barack Obama plans to attend in Cambodia.
Mr Yang, however, repeated China's statements that it is ready to discuss the sea disputes only through bilateral talks. Dealing individually with the countries could give China greater leverage over its smaller neighbours.
"China has sovereignty over the islands in the South China Sea and the adjacent waters. There is plenty of historical and jurisprudence evidence of that," he said, adding that freedom of navigation in the area was assured.
Clinton and her comments on the South China Sea have been strongly criticised in the official Chinese media over the last two days.
Mr Hu gave what may have been another sign of Beijing's unhappiness with Mrs Clinton at the beginning of their talks by praising her only for implementing a student exchange initiative and for "actively" pushing for the construction of the US pavilion at the Shanghai World Expo two years ago.
The US Secretary of State said she also urged China to use "its unique influence" to help bring change to its impoverished and isolated neighbour North Korea, where Kim Jong Un became leader when his father died late last year.
Mrs Clinton is in China at the midpoint of an 11-day, six-nation tour of the Asia-Pacific region that started in the Cook Islands.
After she leaves China, she will visit East Timor and Brunei before heading to Russia's Far East to represent the US at the annual meeting of leaders from the Asia-Pacific Economic Cooperation forum in Vladivostok.