China on Tuesday expressed dissatisfaction and said it had lodged stern representations with the United States after the State Department approved the sale to Taiwan of spare parts for military aircraft worth up to US$330 million.
China lashed out at the deal, saying it "severely violates" global laws and norms governing foreign relations, and expressed "strong dissatisfaction and firm opposition" to the sales.
It was unclear what aspect of worldwide law Geng was referring to. Taiwan would still need to finalize details of the sale with USA companies.
China's Defense Ministry, in a separate statement, also condemned the planned sale, adding that the Chinese military had a "firm and unshakable" resolve to protect the country's sovereignty and territorial integrity.
The United States does not have official diplomatic relations with Taiwan, but must adhere to a USA law requiring that Taiwan has the means to defend itself.
However, the sale is likely to go through, as the Pentagon believes that Taiwan "continues to be an important force for political stability, military balance and economic progress in the region". China as a principle opposes all USA military sales to Taiwan, which split with the mainland in 1949 but which Beijing continues to claim as part of its territory and threatens to invade to bring under its control.
The approval of the sale comes amid heightened tensions between China and the U.S. over a range of issues.
China's purchase of the weapons from Rosoboronexport, Russia's main arms exporter, violated a 2017 law meant to punish the government of Russian President Vladimir Putin for interfering in U.S.
Taiwan's presidential office said the island's government would continue to increase its defence investment and "maintain close communication and cooperation" with the United States on security issues.
The Kremlin dismissed the sanctions as an "unfair" move to undercut Russian Federation as a major arms exporter.
The move brings the amount of Chinese goods hit by duties to more than $250 billion, roughly half of China's USA exports. China last denied such a visit in 2016 amid a spike in tensions between the sides over the disputed South China Sea.