Taiwan is Beijing’s most sensitive territorial issue. Beijing says it is a Chinese province, and has denounced the Trump administration’s support for the island.

Washington has been eager to create a military counterbalance to Chinese forces, building on an effort known within the Pentagon as “Fortress Taiwan”, as Beijing’s military makes increasingly aggressive moves in the region.

The Taipei Economic and Cultural Representative Office in the United States did not respond to a request for comment.

Taiwan’s military is well-trained and well-equipped with mostly US-made hardware, but mainland China has a huge numerical superiority and is adding advanced equipment of its own.

The weapons packages from Lockheed Martin, Boeing and General Atomics were moving their way through the export process, three people familiar with the status of the deals on Capitol Hill said, and a notification to Congress was expected within weeks.

One industry source said US President Donald Trump was expected to be briefed on the packages this week by Secretary of State Mike Pompeo. Some of the deals had been requested by Taiwan more than a year ago but are only now being moved through the approval process. A State Department spokesman declined to comment.

A senior US official, citing Chinese assertiveness in the Taiwan Strait, said: “There is no equilibrium today. It is out of balance. And I think that is dangerous.”

Trump’s White House has made an effort to export weapons to US allies, trying to bolster their defences and decrease dependence on US troops while boosting US companies and jobs.

Other factors include Taiwan’s bigger defence budget and the fear in Taiwan that if Trump loses, Biden would be less willing to sell America’s most advanced weapons to them.

Taiwan’s interest in US weapons and equipment is not new. The island is bolstering its defences in the face of what it sees as increasingly threatening moves by Beijing, such as regular People’s Liberation Army air force and naval exercises near Taiwan.

The senior US official said Taiwan’s increased defence spending was a good step, but it had to do more.

“Taiwan, frankly, needs to do more to ensure that they indigenously have an ability to deter Chinese aggression,” the official said.

Drones that can see over the horizon for surveillance and targeting, coupled with advanced missiles and coastal defences that include smart mines and anti-submarine capabilities to impede a sea invasion, have been discussed at the highest levels to make Taiwan more difficult to attack, like a “porcupine”, according to industry and congressional sources.

A Lockheed Martin-made High Mobility Artillery Rocket System (HIMARS), essentially a truck-based rocket launcher, was among the weapons Taiwan wanted, people familiar with the negotiations said. Taiwan also seeks to buy sophisticated anti-tank missiles.

Rising US-China tensions

Also under discussion are land-based Boeing-made Harpoon anti-ship missiles to serve as a coastal defence against cruise missiles.

Other systems include “underwater sea mines and other capabilities to deter amphibious landing, or immediate attack”, Taiwan’s de facto ambassador to the US said in July.