Since the issue of Taiwan flared up at the beginning of the Trump administration, when the then-newly elected president threatened to use the “one China” policy as a bargaining chip and then backed down, the issue has remained largely on the back burner. Though challenging China on trade, President Donald Trump has opted to remain silent on Taiwan, while cultivating a personal relationship with Chinese President Xi Jinping.

But his administration has made a handful of Taiwan-related moves to anger Beijing and did so again this week with the announcement of a US$330 million arms sale. The deal, which has yet to be finalized, comes after Washington sold $1 billion worth of weapons last year to the independently administered territory, which is claimed as a province of the People’s Republic of China by Beijing.

US arms supplies to Taiwan are a mainstay of Washington’s Taiwan policy, but have prompted perennial outcry from Beijing.

China warned against following through with the proposed transaction, which it said was a breach of basic diplomatic norms as well as the one-China principle.

The move “undermines China’s sovereignty and security interests,” Foreign Ministry spokesman Geng Shuang said on Tuesday, adding that Beijing expresses its “strong dissatisfaction” and “resolute opposition.”

“China urges the US to … immediately cancel the plan to sell arms to Taiwan and end US-Taiwan military ties,” Geng said.

The spokesman stressed that the move would further strain an already fraught relationship between Washington and Beijing.

Hopes for an improvement, or even a maintenance of the current state, of US-China relations have dimmed quickly over the past year, most dramatically on the issue of trade. But conflicting interests in the South China Sea and elsewhere have also come to the fore after they receded to the background during the first year of Trump’s presidency.

It has become increasingly apparent that the current US administration’s policy aims to challenge Beijing on a wide range of disagreements. This week, the news website Axios reported that the White House was preparing a rhetorical and substantive “broadside against China.”

Sources cited in the report said the efforts would be “administration-wide,” including the White House, along with the Treasury, Commerce and Defense departments. One White House official was quoted as saying “we’re not just going to let Russia be the bogeyman.… It’s Russia and China.”

The sources stressed an increasing focus within the administration on cyber theft, election interference, and industrial warfare attributed to China.