TAIPEI: Taiwan will build its own submarines, President Tsai Ing-wen vowed on Tuesday, as the self-ruled island looks to fresh arms sales by the United States, accompanied by key submarine technology, to counter a growing military threat from China.

“Strengthening underwater combat capabilities is most needed in Taiwan’s defence,” Tsai said during a tour of a submarine at the southern naval port of Zuoying, about 350 kilometres (218 miles) from the capital, Taipei.

“This is a problem everyone recognises,” she added. “We have been unable to solve this in the past. As commander of the armed forces, I am determined to solve this problem.”

But the rare appearance of two of Taiwan’s four submarines at the event also spotlighted the island’s slow, sometimes stalled efforts, to upgrade key defence equipment, reported a Taiwanese TV channel.

The black-hulled vessel half-submerged in the water that Tsai visited has been in service for nearly half a century.

“Making a submarine isn’t the problem,” said Gao Chung-hsing, vice president of the National Chung-shan Institute of Technology, a quasi-defence ministry agency responsible for military research and development.

“It is making what kind of submarine that is the problem.”

To build an advanced submarine, for instance, Taiwan, which has never before built such a craft, will have to rely on foreign technology to resolve issues such as integrating the hardware with various electronic systems, defence experts say.

Two submarines in Taiwan’s fleet date from the era of World War Two, were bought from the United States, and are used mainly for training, while the other two, bought from the Netherlands in the 1980s, first saw service in the 1970s.