The US announcement of a $1.42bn arms sale to Taiwan is a not-so-subtle warning shot across the bows of China’s president, Xi Jinping, who is due to meet Donald Trump for potentially tense bilateral talks at next week’s G20 summit in Hamburg. But Trump’s pre-emptive strike could backfire badly.

Official confirmation of the arms sale, under consideration since January, coincided with Xi’s officiation at an ostentatious military parade in Hong Kong on Friday, celebrating China’s reunification with what until 1997 Beijing regarded as a “renegade province” similar to Taiwan.

In a series of parallel, and provocative, moves, a Republican-controlled Senate committee also provisionally approved visits to Taiwan by the Japan-based US Seventh Fleet for the first time since 1979, when Washington recognised the People’s Republic of China and adopted a “one China” policy.

The decision, if implemented, could in effect provide a naval base and facilities for US aircraft carriers and destroyers just off the coast of the Chinese mainland. That’s a bit like the People’s Liberation Army building gun emplacements on Long Island.

The announcement was swiftly applauded in Taiwan, where many view China’s new regional assertiveness as a threat. The defence ministry said: “The ministry welcomes any form of partnership that would enhance Taiwan’s national defence capabilities and bring stability to the region.”

The Senate bill also directs the Pentagon to help Taiwan develop an undersea warfare programme and recommends strengthened strategic cooperation with Taipei.

Coincidentally or not, the US and Australia began their biggest ever joint military exercises on Thursday – a seaborne show of force purposefully directed at China. The battleship exercises, involving 33,000 personnel, reflect heightened tensions over what Washington views as Chinese military expansionism in the South China Sea.

China has expressed “outrage” over the Taiwan arms package. The foreign ministry demanded a halt to the sale and to military drills “to avoid further impairing broadly cooperative China-US relations”. But Beijing’s overall response will depend on the outcome of the Trump-Xi meeting in Hamburg.

When he and Xi first met in April, Trump hailed the start of a new era. “We have great chemistry together,” he declared, and dropped earlier threats to impose punitive trade tariffs and disown the one-China policy.

It transpired his main aim was to persuade Xi to take a tougher line on North Korea. He claimed to have succeeded. But the White House has been briefing in recent days that Trump is disappointed and frustrated at tepid Chinese cooperation on the Pyongyang regime.

So now US action on trade is back on the table. Again not coincidentally, the administration announced further sanctions relating to North Korea’s nuclear and missile programmes on Thursday, targeting a Chinese bank and a shipping company.

It also pointedly criticised China’s human rights and democracy record in Hong Kong. The US moves have sparked speculation about a new slump in bilateral relations but this is probably premature. None of the latest US actions is irreversible. Trump is crudely reminding Xi of possible consequences if their talks do not produce results. But China has a history of reacting badly to bullying and Trump’s tactics could blow up in his face.

In Taiwan, where many in the independence-minded, ruling Democratic Progressive party feel serially bullied by Beijing, indications of closer American engagement could raise false hopes and dangerously exacerbate strains with the mainland. China’s recent success in inducing Panama to break off diplomatic ties with Taipei, the latest example of Beijing’s attempts to isolate the island, was much resented.

Opinion polls suggest increasing numbers of younger Taiwanese, impatient with Chinese pressure to alter the status quo, are moving in the opposite direction to that which China wants: towards greater separation.

A recent Taiwan Brain Trust thinktank survey found that nearly 90% supported “normalisation” of Taiwan’s political status internationally, prospectively meaning worldwide recognition of Taiwan as an independent, sovereign nation.

As in Hong Kong, Taiwanese citizens increasingly feel different from China; 75% said Taiwan and China were separate nations. Only 11% backed unification. And when they see Xi and his troops strutting around Victoria Harbour, who can blame them?