US Secretary of State Hillary Clinton has urged South East Asian nations to work together to resolve territorial disputes in the South China Sea.
Speaking in Indonesia during her tour of the region, Mrs Clinton said the Asean bloc and China must make "meaningful progress" towards drafting a code of conduct for the disputes.
China has competing territorial claims against four Asean member states.
The rows have led to increased tensions in the region and fears of conflict.
At a news conference with her Indonesian counterpart in the capital, Jakarta, Mrs Clinton said the US did not take a position on territorial disputes.
"But we believe the nations of the region should work collaboratively to resolve disputes without coercion, without intimidation and certainly without the use of force," she said.
"That is why we encourage Asean and China to make meaningful progress toward finalising a comprehensive code of conduct in order to establish rules of the road and clear procedures for peacefully addressing disagreements."
Indonesia has played a leading role in drafting the code of conduct, which China has so far been reluctant to sign up to, preferring to negotiate with individual countries.
Indonesian Foreign Minister Marty Natalegawa agreed with Mrs Clinton on the need for the code, saying that without it, "we can be certain of more incidents and tension for our region".
US 'at fault'
Mrs Clinton flew in to Indonesia from the Cook Islands, where she attended a Pacific summit. She will later meet Indonesian President Susilo Bambang Yudhoyono.
She is also scheduled to visit China, East Timor and Brunei before heading to the Apec forum in Russia.
Her extended visit is being seen as a sign that the US is stepping up its diplomatic offensive in the region, as part of President Barack Obama's "pivot to Asia" in the face of an assertive China.
China has overlapping claims with four Asean members in the South China Sea. Earlier this year, vessels from China and the Philippines faced off for several weeks over one area, the Scarborough Shoal.
At a regular meeting hosted by Cambodia in July, Asean failed for the first time in its 45-year history to issue a joint statement because of tensions over the disputes.
Vietnam and the Philippines have accused host Cambodia of yielding to Chinese pressure to keep the issue off the agenda.
Since then, Mr Natalegawa has visited regional leaders in a bid to encourage co-operation and the implementation of a joint code of conduct for all parties who claim the various islands.
Mrs Clinton flies to China after Indonesia for two days of talks. Defense Secretary Leon Panetta is also due in China later this month.
On Monday a commentary by China's state-run Xinhua news agency said the US needed to prove it was "returning to Asia as a peacemaker, instead of a troublemaker".
The security situation in the region was worsening, it said, because South China Sea and East China Sea territorial disputes were escalating.
"Washington, which claims not to take sides in the disputes, is partly blamed for fuelling the tensions because it has apparently emboldened certain relevant parties to make provocations against China in order to achieve undeserved territorial gains," the commentary said.