U.S. Vice President Joe Biden and Japan Prime Minister Shinzo Abe on Thursday, Dec 12 discussed tensions with China in the East China Sea and stressed the importance of security cooperation between the United States, Japan and South Korea, Reuters reported.

China's declaration in late November of an "air defense zone" around disputed islands claimed by both China and Japan in the East China Sea has triggered turmoil in the region.

The issue dominated a trip to Japan, China and South Korea that Biden made early this month.

In the phone call with Abe, Biden reaffirmed that the United States does not recognize the so-called air defense zone and that the announcement will in no way affect U.S. military operations in the East China Sea.

Biden reiterated U.S. support for steps to reduce regional tensions, such as new bilateral mechanisms for crisis communication.

"The vice president also reinforced the importance of trilateral security cooperation among the United States, Japan and the Republic of Korea, and noted our continued support for improved relations between Tokyo and Seoul," a statement from Biden's office said.

The two leaders also discussed negotiations aimed at achieving a Trans-Pacific Partnership trade agreement and agreed on the need to resolve sensitive issues, including on agriculture and autos, Biden's office said.