U.S. officials have expressed concern that an international court ruling expected in coming weeks on a case brought by the Philippines against China over its South China Sea claims could prompt Beijing to declare an air defense identification zone, or ADIZ, as it did over the East China Sea in 2013.

“We would consider an ADIZ…over portions of the South China Sea as a provocative and destabilizing act which would automatically raise tensions and call into serious question China’s commitment to diplomatically manage the territorial disputes of the South China Sea,” Kerry said during a visit to Mongolia.

“So we urge China not to move unilaterally in ways that are provocative.”

Kerry will visit China after Mongolia.

http://www.reuters.com/article/us-southchinasea-usa-china-idUSKCN0YR01