The United States has approved a possible $100 million sale of equipment and services to Taiwan to "sustain, maintain, and improve" the Patriot missile defense system used by the self-ruled island claimed by China, the Pentagon said Monday.

A statement from the U.S. Defense Security Cooperation Agency said it had delivered the required certification notifying Congress following State Department approval for the sale, which was requested by Taiwan's de facto embassy in Washington.

Upgrades to the Patriot Air Defense System would "help improve the security of the recipient and assist in maintaining political stability, military balance, economic and progress in the region," the DSCA said in a statement.