China will come under the most concerted diplomatic pressure yet to rein in its assertive moves in the disputed South China Sea when the United States uses a regional security meeting this weekend to rally support for a freeze on provocative acts.
The push by U.S. Secretary of State John Kerry at the ASEAN Regional Forum marks a step up in Washington's involvement in the dispute, which has frayed regional ties as China acts more forcefully on its sweeping sovereignty claims.
Kerry arrives in Myanmar's capital Naypyidaw on Saturday, joining top diplomats from China, Russia, Japan, India, Australia, the European Union and Southeast Asia among others in Asia's highest-profile gathering so far this year. Foreign ministers of the 10-member Association of Southeast Asian Nations (ASEAN) begin talks on Friday.
Beijing rejects U.S. involvement in the dispute and has already dismissed proposals from Washington and Manila for a freeze on actions such as land reclamation and construction on disputed islands and reefs.
"The secretary is not looking for a showdown. This is not a superpower battle," said a senior U.S. State Department official, stressing that Kerry would call on all claimants to show restraint, not just China.
Washington, however, has singled China out.
Daniel Russel, the State Department's senior diplomat for the East Asia region, said in a speech on July 28 that public evidence indicated China's upgrading of outposts on small land features in the South China Sea was "far outpacing" similar work other claimants were doing.
On Thursday, Chinese state media said China planned to build lighthouses on five islands in the South China Sea. At least two of the islands - Drummond Island and Pyramid Rock - are in the Paracel Islands, which are also claimed by Vietnam and Taiwan.
The unusually strong U.S. stance will add pressure on Beijing to address growing regional concerns and could encourage some ASEAN nations to push for faster progress on a maritime code aimed at reducing tensions. China accuses the United States of emboldening claimants such as the Philippines and Vietnam with its military "pivot" back to Asia.
"The Americans have decided that based, not on what China is saying, but what it is doing, they had to lift their game," said Ernest Bower, a Southeast Asia expert at the Center for Strategic and International Studies in Washington.