Taiwan's Ministry of National Defense thanked the United States on Friday for selling four Perry-class frigates to the island despite opposition from China.

The ministry said Washington's move reaffirms U.S. support for the Taiwan Relations Act enacted in 1979 by the U.S. Congress to sustain substantive relations with Taiwan after Washington severed diplomatic ties and switched allegiance to Beijing.

Since then, every administration has sold arms to Taiwan, without exception.

U.S. President Barrack Obama signed into law Dc. 18 a bill authorizing the sale of the Perry-class guided missile frigates to Taiwan, the second arms deal he has approved.

During Obama's first term, Washington agreed to upgrade Taiwan's fleet of F-16 A/B fighter jets.

Since President Ma Ying-jeou took office in May 2008, Washington has agreed to sell defensive weapons worth $18.3 billion, including the F-16 A/B upgrades, 30 AH-64E Apache attack helicopters and 12 P-3C Orion antisubmarine and maritime surveillance aircraft.

But when the U.S. Senate passed the Naval Vessel Transfer Act authorizing the sale of the four frigates to Taiwan on Dec. 4, Beijing lodged a protest with Washington, saying the move would put the United States in violation of the 1982 Sino-U.S. Communique on Arms Sales to Taiwan.

Beijing has called for the sale to be scrapped and charged Washington would violate a provision in the communique saying the United States agreed not to interfere in China's internal affairs.

When the House of Representatives passed the bill in April, China also protested.

Taiwan and China have been governed separately since they split amid a civil war in 1949.

Beijing has since then endeavored to isolate Taiwan, which it regards as a renegade province awaiting reunification.

Despite close and growing economic ties, they still view each other as political rivals.