WASHINGTON, D.C.: The US Senate has unanimously approved an amendment that reaffirms the US commitment to Japan in its territorial dispute with China over the Senkaku Islands as Washington tries to counter any attempt by Beijing to challenge Japan’s administration of the archipelago.

The measure was attached on Thursday to the National Defense Authorization Bill for Fiscal Year 2013 still being debated in the Senate. Senators Jim Webb of Virginia, James Inhofe of Oklahoma, Joe Lieberman of Connecticut and John McCain of Arizona have co-sponsored the measure.

The amendment notes that while the United States “takes no position” on the ultimate sovereignty of the territory, it, however, “acknowledges the administration of Japan over the Senkaku Islands.”

It further adds that “unilateral actions of a third party will not affect United States acknowledgement of the administration of Japan over the Senkaku Islands.”

The legislation reaffirms the US commitment to Japan under the Treaty of Mutual Cooperation and Security and warns that an armed attack against either party “in the territories under the administration of Japan” would be met in accordance with its provisions.

The amendment also noted US opposition to any efforts to coerce, threaten or use force to resolve territorial issues.

The Senate reiterated the US national interest in freedom of navigation, peace and stability, respect for international law and unimpeded lawful commerce in the region.

The sovereignty of the islands has been a source of friction for decades, but the row erupted earlier this year after the nationalist governor of Tokyo said that he wanted to buy them for the city, forcing the Japanese government to nationalize them.

Chinese vessels have been spotted in and around the territorial waters every day for the last month.

Both sides have publicly refused to back down on their respective claims to the Japan-controlled islands, known as Senkaku in Japan and Diaoyu in China.

National pride as well as potential mineral reserves are at stake in the decades-old dispute, which has hit the huge trade relationship between the world’s second and third largest economies.