In the Indo-Pacific region, only Australia and Indonesia now operate the system, three of which the US said last year Taiwan would receive as part of a US$2 billion weapons sale, Reuters reported.

The National Advanced Surface-to-Air Missile System (NASAMS) medium-range air defense solutions, as they are called, are made by RTX, and are a new weapon for Taiwan.

The Pentagon said the company was given a firm fixed-price contract for procurement of the NASAMS units, with work estimated to be completed in February 2031.

"Fiscal 2026 foreign military sales (Taiwan) funds in the amount of US$698,948,760 were obligated," it said in a statement.

RTX did not immediately respond to a request for comment.

Used in Ukraine to defend against the Russian invasion, the NASAMS system offers a sharp boost in air defense capabilities that the US is exporting to Taiwan as demand for it surges.

The US approved the sale of fighter jet and other aircraft parts to Taiwan for US$330 million on Nov 13, in the first such deal since President Donald Trump took office in January, prompting thanks from Taipei and anger in Beijing.

The arms sales news comes amid a worsening diplomatic crisis between Beijing and Tokyo over Taiwan, claimed by China as its own territory.

On Nov 16, Chinese coast guard ships sailed through waters around a group of East China Sea islands controlled by Japan but claimed by China.

Japan said it also scrambled fighter jets on Nov 15, after China flew a drone between Taiwan and Japan’s westernmost island of Yonaguni.

Asked about the tension on Nov 19, Taiwan Defense Minister Wellington Koo said China should not resort to force to resolve disputes.

“China should abandon its thinking of using force to resolve things,” he told reporters.

Taiwan’s military is beefing up its armaments to better tackle any attack from China, through efforts such as building its own submarines to defend vital maritime supply lines.

China’s military operates around Taiwan on an almost daily basis in what Taipei views as a “grey zone” strategy to test and exhaust Taiwan’s forces.

The US is bound by law to provide Taiwan the means to defend itself, despite a lack of formal diplomatic ties, to the constant anger of Beijing.