China angrily warned the United States on Saturday that a plan to sell $6.4 billion in arms to Taiwan would seriously harm already-strained ties. One Chinese expert said the sale would give Beijing a "fair and proper reason" to accelerate weapons testing. The U.S. is "obstinately making the wrong decision," China's Foreign Ministry said in a statement on its Web site. It said Vice Foreign Minister He Yafei warned the U.S. Embassy that the planned sale would "cause consequences that both sides are unwilling to see" and "seriously harm U.S.-Sino relations." He urged that it be immediately canceled, it said. A spokeswoman for the U.S. Embassy, Susan Stevenson, confirmed that China expressed its views, and said the embassy had no comment. A notification of the planned sale posted Friday on a Pentagon Web site said it would include 60 UH-60M Black Hawk helicopters, 114 Patriot Advanced Capability-3 missiles, mine hunting ships and information technology. U.S. lawmakers have 30 days to comment on the proposed sale; without objections, it would proceed. Taiwan is the most sensitive issue in U.S.-China relations, with the potential to plunge into conflict two powers increasingly linked in security and economic issues. China claims the self-governing island as its own, while the United States is Taiwan's most important ally and largest arms supplier. China vehemently opposes U.S. arms sales to Taiwan, and has threatened to invade should it ever formalize its de facto independence. The United States, which told China of the sale only hours before the announcement, acknowledged that Beijing may retaliate by temporarily cutting off military talks with Washington, which happened after the former Bush administration announced a multibillion-dollar arms sale to Taiwan in 2008. "Maybe the People's Liberation Army will accelerate weapons testing, because this time we have a fair and proper reason to do so," said Jin Canrong, a professor of international studies at China's Renmin University. The package, however, dodges a thorny issue: the F-16 fighter jets that Taiwan covets are not included. The Pentagon's decision not to include the fighters and a design plan for diesel submarines two items Taiwan wants most "shows that the Obama administration is deeply concerned about China's response," said Wang Kao-cheng, a defense expert at Taipei's Tamkang University. China has more than 1,000 ballistic missiles aimed at Taiwan. The U.S. government is bound by law to ensure the island is able to respond to Chinese threats.