Beijing is firmly opposed to the U.S. State Department's approval of an arms sale to Taiwan and has lodged solemn representations with the U.S. side, the Foreign Ministry said in a statement issued on Thursday.
China will resolutely take legitimate and necessary countermeasures in light of the development of the situation, the statement said.
The Pentagon's Defense Security Cooperation Agency announced on Wednesday that the U.S. State Department had approved the sale of 40 Medium Self-Propelled Howitzer artillery systems to Taiwan in a deal valued at $750 million.
The agency said the decision was made following the request from the Taipei Economic and Cultural Representative Office in the U.S. and the deal would help the island maintain its defensive capabilities.
The Foreign Ministry statement said the decision jeopardized China-U.S. relations, as well as peace and stability across the Taiwan Straits.
Taiwan is an inalienable part of China, and the United States has interfered in China's internal affairs and undermined China's sovereignty and security interests by selling arms to Taiwan, it said.
Such an act runs counter to international law and basic principles of international relations, and it violates the one-China principle and the provisions of the three China-U.S. joint communiques, especially the August 17 Communique, it said.
The U.S. must stop arms sales to and military interactions with Taiwan, and immediately cancel the planned arms sales to Taiwan, it said, as the move would "cause more damage to China-U.S. relations and peace and stability across the Taiwan Straits".
Zhu Fenglian, a spokeswoman for the Taiwan Affairs Office of the State Council, also expressed opposition to the decision on Thursday, urging the U.S. to stop any arms sales to Taiwan.
Zhu said, "We urge the U.S. not to send a wrong signal to the separatist forces, endanger peace and stability across the Taiwan Straits and harm the well-being of compatriots on both sides of the Straits."
She said the attempts of Taiwan's ruling Democratic Progressive Party to rely on the U.S. to seek "independence" will only "push the people of Taiwan into disaster".
Tang Yonghong, deputy director of the Taiwan Research Center at Xiamen University, said U.S. arms sales to Taiwan have become regular and the weapons sold to the island are increasingly sophisticated.
"The proposed sale this time showed that the U.S. will continue its strategy of using the island to contain China," Tang said, adding that the U.S. had ignored China's three red lines－including not infringing upon China's sovereignty and harming China's territorial integrity, which were set out when U.S. Deputy Secretary of State Wendy Sherman visited Tianjin last month.
"The Chinese government should take concrete actions to counter the repeated provocations from the collusion of the U.S. and Taiwan authorities, and make them pay a heavy price," he said.
Since the Biden administration took office, it has repeatedly reaffirmed its one-China policy and made clear that it doesn't support "Taiwan independence". However, it has repeatedly tested China's bottom line by its actions, including sending a U.S. senator to visit Taiwan by military aircraft and landing a U.S. military transport plane in Taiwan, according to Tang.
"The U.S. has been playing a two-handed strategy on the Taiwan question for its own benefits," he said. "While claiming its adherence to its so-called one-China policy, it has been developing substantive relations with the island."
"It can be predicted that the U.S. will continue to maintain diplomatic relations with China, but meanwhile, regarding China as its main strategic competitor, it will use all kinds of means to suppress China, and playing the Taiwan card is seen by the U.S. as a handy way to do this."
