The government is looking to buy 218 AMRAAM medium range air-to-air missiles and another 235 Maverick missiles, at an estimated cost of $421 million.
The purchase is aimed at modernizing Taiwan's military and enhancing its ability to counter air-to-ground threats. The missiles would be used by Taiwan's F-16 fighters. Taiwan announced in July that it is also hoping to buy 66 F-16s from Washington.
"China is improving its military power and we treat that as a threat," Rear Adm. Wu Chi-fang, a Defense Ministry spokesman, said Saturday.
A statement on the proposed sale issued earlier this week said it would improve Taiwan's security and promote "political stability, military balance and economic progress in the region."
The deal has not been concluded, however, and it immediately prompted opposition from China, which considers Taiwan to be a part of its sovereign territory and has in the past strongly protested similar weapons sales.
"China is firmly opposed to the sale of weapons by the United States to Taiwan," Foreign Ministry spokesman Qin Gang said in a statement posted Friday on the ministry's Web site.
Qin said the proposed sale would "seriously violate" previous commitments made by Washington to reduce arms sales to Taiwan and would represent a "rude interference into China's internal affairs."
The announcement of the plan comes amid heightened concerns in Taiwan that advances in China's military, and particularly in its missile capabilities, are posing an increasing threat.
In January, China conducted a successful anti-satellite test, blasting a weather satellite out of orbit with a ground-based missile. President Chen Shui-bian said last month that China has installed nearly 1,000 missiles on its east coast, targeting Taiwan.
Chen said China has increased its total number of missiles from 200 seven years ago to 988.
Taiwan's military says the island's weapons supplied by Western nations are more advanced, and the training of military personnel is better than their equivalents in China, the AP says.
But to maintain a chance of victory in a possible conflict, Taiwan's government has said it needs a US$16 billion (euro13 billion) U.S. arms package that includes submarines, Patriot missiles and anti-submarine aircraft.
In December, the island's Legislature sent part of a long-delayed U.S. arms deal package to a budgetary committee for consideration.
But the deal still faces an uphill battle.
Taiwan's opposition used its slight majority in the 219-seat Legislature to block the purchase for two years on the grounds it would propel Taiwan into a no-win arms race with its communist rival.
In July, Taiwan submitted a formal request to procure 66 U.S.-made F-16 C and D fighter jets. The U.S. been cautious over that sale because of the delays in approving the larger weapons package.
Annual U.S. military sales to Taiwan total about US$1 billion (Ђ775 million), and account for some 90 percent of the island's imports of foreign weapons.