The US State Department has cleared the potential sale of four sophisticated US-made aerial drones to Taiwan in a notification sent to Congress, the last step before finalising a weapons sale that will further anger China.
The $US600 million ($A839 million) deal would be the first since US policy on the export of closely guarded drone technology was loosened by the Trump administration.
Recent reports have detailed the US moving ahead with four other sales of military equipment to Taiwan, with a total value of around $US5 billion, as it ramps up pressure on China and concerns rise about Beijing's intentions toward the island.
Beijing considers Taiwan a wayward province it has vowed to bring under control, by force if necessary.
Washington considers it an important democratic outpost and is required by law to provide it with the means to defend itself.
In response to the sales, China's Ministry of National Defense said on October 27, "China strongly urges the US side to immediately withdraw plans of arms sales to Taiwan, cease US-Taiwan military contacts and stop selling weapons to the island".
In Taipei, Taiwan's foreign ministry thanked the US government for its "security assurance" and said the arms sales will further boost Taiwan's defence capacity.
The US State Department's formal notification gives Congress 30 days to object, which is unlikely given broad bipartisan support for the defence of Taiwan.
The four MQ-9 SeaGuardian drones, made by General Atomic Aeronautical System of San Diego, would come with associated ground stations, spares and training.
While the drones are armable, they will be outfitted with surveillance equipment.