The deal includes anti-missile defences and helicopters
China has expressed its outrage over a proposed US weapons sale to Taiwan, worth $6.4bn (£4bn), including helicopters and missiles.
Chinese Vice Foreign Minister He Yafei said the move would have a "serious negative impact" on co-operation between the US and China.
Ties between China and the US are already strained by rows over trade and internet censorship.
Beijing considers Taiwan a breakaway province of China.
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Taiwan split from China at the end of the country's civil war in 1949.
Beijing has hundreds of missiles pointed at the island and has threatened in the past to use force to bring it under its control.
Strained relations
"The United States' announcement of the planned weapons sales to Taiwan will have a seriously negative impact on many important areas of exchanges and co-operation between the two countries," Mr He said.
"This will lead to repercussions that neither side wishes to see," he said, urging Washington to halt the planned sale.
The Pentagon earlier notified the US Congress of the proposed arms sale, which included helicopters and Patriot anti-missile defences.
The weapons are part of a package first pledged by the Bush administration.
PROPOSED ARMS SALE 114 Patriot missiles ($2.81bn) 60 Black Hawk helicopters ($3.1bn) Communication equipment ($340m) 2 Osprey mine-hunting ships ($105m) 12 Harpoon missiles ($37m) Source: Defense Security Co-operation Agency
Friday's notification to Congress by the Defense Security Co-operation Agency (DSCA) was required by law. It does not mean the sale has been concluded.
US lawmakers have 30 days to comment on the proposed sale, Associated Press reported. If there are no objections, it would proceed.
The arms package includes 114 Patriot missiles, 60 Black Hawk helicopters and communications equipment for Taiwan's F-16 fleet, the agency said in a statement.
It does not include F-16 fighter jets, an item highly desired by Taiwan's military.
Beijing has previously warned the US not to go ahead with arms sales to Taiwan. Ties between China and the US are already strained by rows over trade and internet censorship.
The DSCA said the proposed sale would support Taiwan's "continuing efforts to modernise its armed forces and enhance its defensive capability."
It added: "The proposed sale will help improve the security of the recipient and assist in maintaining political stability, military balance, and economic progress in the region."
The US is the leading arms supplier to Taiwan, despite switching diplomatic recognition from Taipei to Beijing in 1979.
China has stated that they will cease all military exchanges with the United States in response to a  weapons deal with Taiwan going ahead. He Yafei, Chinese Vice-Foreign Minister, said that there would be a "serious negative impact" with regards to the relationship between the US and China.

Taiwan and mainland China have been ruled by separate governments since 1949, and neither recognize each other's independence. In an effort to regain control of Taiwan, the government in Beijing has been open to running the island like Hong Kong, in a "one country, two systems" manner, but people in Taiwan support the status quo. The Chinese defense ministry said that they had "decided to suspend planned mutual military visits". They "strongly demand" that the United States "respect the Chinese side's interests," calling for the proposal to be rejected.

China summoned the US Ambassador to China, Jon Huntsman, to warn the US Government about the consequences, and to urge for cancellation of the deal. The Pentagon proposed the deal, that was first promised during the later days of the Bush administration, to Congress earlier.

Yafei issued a statement on the Foreign Ministry website stating that "the United States' announcement of the planned weapons sales to Taiwan will have a seriously negative impact on many important areas of exchanges and co-operation between the two countries."

However, the US is defending itself. "Such sales contribute to maintaining security and stability across the Taiwan Strait", Laura Tischler, spokeswoman for the US State Department, said.

Beijing is threatening to review co-operation on major issues and impose sanctions on companies selling arms, even though US companies are banned from selling arms to China as a result of the Tiananmen Square massacre in 1989, so it is not clear what the effect will be. A Chinese defence ministry spokesman said that the sanctions reflected the "severe harm" the deal would have. A foreign ministry spokesman stated that there would be "repercussions that neither side wishes to see" if the deal went ahead.

Taiwan, one of Asia's few functioning democracies, welcomed the proposal, with Taiwanese president Ma Ying-jeou being quoted as saying "It will let Taiwan feel more confident and secure so we can have more interactions with China."

The arms deal includes UH-60 Black Hawk helicopters, communications equipment and MIM-104 Patriot missiles, but does not include the F-16 fighter jets that Taiwan's military were looking for. The US is legally obliged to supply Taiwan with defensive weapons under the Taiwan Relations Act 1979.

In 2003, an unnamed US briefing stated that "the US would have to get involved if China tried to use coercion or force to unilaterally change the status of Taiwan".