WASHINGTON (REUTERS) - China's aggressive military drills around Taiwan in response to US House Speaker Nancy Pelosi's visit put Washington on edge, but not enough to spur an immediate sharp increase in weapons sales to the island, sources told Reuters.

President Joe Biden's administration and US lawmakers stress their ongoing support for the government in Taipei, and there are items in the approval pipeline for Taiwan that could be announced in the coming weeks or months.

But the focus will be on sustaining Taiwan's current military systems and fulfilling existing orders - rather than offering new capabilities more likely to inflame already red-hot tensions with China, said three sources, who requested anonymity due to the sensitivity of the issue.

"I think there will be an attempt to push stuff to Taiwan, and not just weapons. Supplies, should there - God forbid - be an embargo. More munitions. Lower-level stuff," one source close to political-level talks on US-Taiwan arms sales said.

Such approvals could be announced as soon as September, the sources said, noting it would be a signal that Beijing's blockade-style drills following Mrs Pelosi's early August visit had not shaken US support.

Critics of the administration's approach argue those drills, China's largest ever around the island, should be a wake-up call to encourage Washington to do more for Taiwan.

For its part, Taiwan on Thursday proposed a 13.9 per cent year-on-year increase to a record US$19.41 billion (S$27 billion) in its defence budget for next year.

A blockade, for example, would challenge one of the core tenets of the United States' Taiwan Relations Act, which defines any boycott or embargo toward Taiwan as a threat to greater security in the Western Pacific. The law also requires US provision of equipment for Taiwan's self-defence.

White House Indo-Pacific coordinator Kurt Campbell - asked during a recent briefing whether the administration was considering both invasion and blockade scenarios - said defence sales would be designed to meet "the evolving security circumstances that Taiwan faces."

Both scenarios, Mr Campbell said, "are indeed taken into our calculus, and you will see that going forward."

Since 2017, US presidents have approved more than US$18 billion in arms sales to the Chinese-claimed island, the largest portion of that coming in the second half of the Trump administration. But new approvals have slowed under Biden, amid delivery backlogs and reports of disagreement between Washington and Taipei over what the island needs.

Taiwan's de facto ambassador to the United States, Hsiao Bi-khim, told Reuters last week that following China's drills there was still a "practice of continuing arms sales".

"I think what we are trying to do is ensure that these are regularised, normalised processes," Ms Hsiao said.

"In earlier years they would put big packages together, wait a few years to make a big announcement. That's no longer the practice. Our requests are reviewed on a case-by-case basis, and we will proceed as such," she said.

The White House National Security Council did not respond to a request for comment.

'A lot on the line'

Support for Taiwan is strong from both Mr Biden's fellow Democrats and Republicans in Congress, where lawmakers are writing several bills to strengthen ties.

"There's a lot on the line. Democracy's on the line," Democratic Representative Gregory Meeks, who travelled to Taiwan with Mrs Pelosi, told Reuters in an interview.

Mr Meeks, who reviews major international arms deals as chairman of the House Foreign Affairs Committee, declined comment on the timing or scope of any new weapons announcement.

He said Taiwan's leaders had not expressed frustration about the pace of weapons deliveries.

On Friday, Taiwan's president, Ms Tsai Ing-wen, told US Senator Marsha Blackburn, the latest US lawmaker to travel to the island, that recent US visits had reinforced Taiwan's determination to defend itself.

Ms Bonnie Glaser, a Taiwan expert at the German Marshall Fund think tank, said Taiwan's priority appeared to be securing deliveries of the substantial backlog of prior arms sales requests. Those include hundreds of shoulder-fired Stinger anti-aircraft missiles and Harpoon anti-ship missile launchers, the latter deal set for December 2028 completion, according to Pentagon contracting data.

China has never ruled out using force to bring Taiwan under its control, and says Washington's arms sales are what undermine the status quo across the Taiwan Strait.

Taipei says the People's Republic of China has never ruled the island and has no right to claim it.

US officials want to ensure any weapons sold to Taiwan are appropriate - namely cheap, mobile, and resilient - to stave off any possible attack from much larger Chinese forces.

Taiwan signalled in May that it had abandoned a plan to buy advanced new anti-submarine warfare helicopters from the United States, saying they were too expensive, although Taiwan media said Washington had rejected the sale as not being in line with the island's needs.

The United States was never keen to sell the MH-60R helicopters to Taiwan, assuming they would be quickly destroyed in a conflict with China, according to three people familiar with talks.

US-Taiwan Business Council President Rupert Hammond-Chambers has criticised the Biden administration's approach to new approvals as too restrictive, and saw no change forthcoming.

"I'm not expecting new notifications in the coming months bar more sustainment, and possibly some munitions," he said.