China vowed "resolute countermeasures" on Sunday to a recently approved US arms sale to Taiwan, saying it had lodged a complaint over the sale, which it said seriously infringes on China's sovereignty.
The US State Department approved the potential sale, worth an estimated $385 million, of spare parts and support for F-16 jets and radars to Taiwan, the Pentagon said on Friday.
The sale was announced hours before Taiwan's President Lai Ching-te left on a visit to Taipei's three diplomatic allies in the Pacific, with stops in Hawaii and the US territory of Guam.
China's Taiwan Affairs Office said it "firmly opposes" Taiwan President Lai Ching-te transiting in the US after the latter landed in Hawaii on Saturday, with plans to visit Guam.
The arms sale sends "a wrong signal" to Taiwan independence forces and undermines US-China relations, China's foreign ministry said in a statement.
China, which views democratically governed Taiwan as its own territory and the most important issue in its relations with Washington, strongly dislikes Lai, calling him a "separatist".
The United States is bound by law to provide Taiwan with the means to defend itself despite the lack of formal diplomatic ties between Washington and Taipei, to the constant anger of Beijing.
Taiwan rejects China's claims of sovereignty.