The Obama administration formally notified Congress on Wednesday of a $1.83 billion arms sale package for Taiwan, including two frigates, anti-tank missiles, amphibious assault vehicles and other equipment, drawing an angry response from China.
The authorization, which Reuters on Monday reported was imminent, came a year after Congress passed legislation approving the sale. It is the first such major arms sale to Taiwan in more than four years.
The White House said there was no change in the longstanding US "one China" policy. Past US weapons sales to Taiwan have attracted strong condemnation in China, which considers Taiwan a renegade province.
The White House said the authorization followed previous sales notifications by the administration totaling over $12 billion under the Taiwan Relations Act.
"Our longstanding policy on arms sales to Taiwan has been consistent across six different US administrations," a National Security Council spokesman, Myles Caggins, said. "We remain committed to our one-China policy," he added.
Although Washington does not recognize Taiwan as a separate state from China, it is committed under the Taiwan Relations Act to ensuring Taipei can maintain a credible defense.
The sales come at a period of heightened tensions between the United States and China over the South China Sea, where Washington has been critical of China's building of man-made islands to assert expansive territorial claims.
China summoned the US charge d'affaires in Beijing, Kaye Lee, to protest and said it would impose sanctions on the companies involved, China's state news agency Xinhua reported.
"Taiwan is an inalienable part of China's territory. China strongly opposes the US arms sale to Taiwan," Xinhua quoted Vice Foreign Minister Zheng Zeguang, who summoned Lee, as saying.
Zheng said the sales went against international law and basic norms of international relations and "severely" harmed China's sovereignty and security.
"To safeguard our national interests, China has decided to take necessary measures, including imposing sanctions against the companies involved in the arms sale," Zheng said.
The US State Department said Raytheon and Lockheed Martin were the main contractors in the sales.
It was not clear what impact sanctions might have on the companies, although in 2013, Lockheed Martin signed an agreement with the Thailand-based Reignwood Group to build an offshore plant to provide energy for a luxury resort on Hainan island in southern China.
Taiwan's defense ministry said in a statement the new weapons would be phased in over a number of years and would enable Taiwan to maintain and develop a credible defense.
US State Department spokesman John Kirby said the decision was based solely on Taiwan's defense needs.
"The Chinese can react to this as they see fit," he said. "This is nothing new. ... There's no need for it to have any derogatory effect on our relationship with China."
Kirby said Washington wanted to work to establish a "better, more transparent more effective relationship" with China in the region and had been in contact with both Taiwan and China on this on Wednesday. He declined to elaborate.
David McKeeby, another State Department spokesman, said the arms package included two Perry-class guided-missile frigates; $57 million of Javelin anti-tank missiles made by Raytheon and Lockheed Martin; $268 million of TOW 2B anti-tank missiles and $217 million of Stinger surface-to-air missiles made by Raytheon, and $375 million of AAV-7 Amphibious Assault Vehicles.
The State Department said the frigates were being offered as surplus items at a cost of $190 million. The package also includes $416 million of guns, upgrade kits, ammunition and support for Raytheon's Close-in Weapons System.
Analysts and congressional sources believe the delay in the formal approval of the sales was due to the Obama administration's desire to maintain stable working relations with China, an increasingly powerful strategic rival but also a vital economic partner as the world's second-largest economy.
US Republican lawmakers said on Wednesday they were pleased the administration had authorized the sale but called for a more regular process for such transactions.
John McCain, chairman of the Senate Armed Services Committee, said this would "avoid extended periods in which fear of upsetting the U.S.-China relationship may harm Taiwan's defense capabilities." (Reporting by Patricia Zengerle and David Brunnstrom; Addtional reporting by Matt Spetalnick; Editing by Susan Heavey, Andrew Hay and Leslie Adler)