The United States sees China's introduction of an oil rig and several government vessels in waters disputed with Vietnam as "provocative", U.S. Secretary of State John Kerry told China's foreign minister in a telephone call on Monday.
"He urged both sides to de-escalate tensions, ensure safe conduct by their vessels at sea, and resolve the dispute through peaceful means in accordance with international law," U.S. State Department spokeswoman Jen Psaki said.
In separate remarks to Singapore's visiting Foreign Minister K. Shanmugam, Kerry said the United States was deeply concerned by China's "aggressive act" in the dispute.
"We are particularly concerned - all nations that are engaged in navigation and traffic within the South China Sea, the East China Sea, are deeply concerned about this aggressive act," Kerry said in the Monday meeting.
"We want to see a code of conduct created; we want to see this resolved peacefully through the Law of the Sea, through arbitration, through any other means, but not direct confrontation and aggressive action," Kerry added, according to a transcript of his comments released by the State Department.
(Reporting by Nick Macfie; Writing by Clarence Fernandez)