Beijing - China has summoned the US envoy to protest Washington's sale of warships to Taiwan, as part of a massive $1.8 billion (S$2.54 billion) arms package, Beijing said Thursday.
Taipei will get an array of missiles, amphibious assault vehicles and two frigates in the latest deal, which comes as the United States looks to shore up its Asian friends and allies in the face of growing Chinese assertiveness.
"China staunchly opposes America's sale of arms to Taiwan," a statement from the country's foreign affairs ministry said, as US charge d'affaires Kaye Lee was called in for a dressing down.
It said Beijing would impose sanctions on any companies involved in the sale, and warned Washington to cancel the deal to "avoid causing further damage to Sino-US relations".
Although it has been governed separately since the end of a civil war in 1949, China considers Taiwan a renegade province awaiting reunification.
It regularly lashes out at Washington and other powers for their dealings with Taipei, which it labels "interference" in Chinese domestic affairs.
The US weapons sale - the first to Taiwan in four years - comes at an increasingly febrile time in East Asia, where China's aggressive position on territorial disputes with its neighbours has raised anxiety levels in the US and among allies from Japan to the Philippines.
Beijing is building islands with military-grade airstrips in the South China Sea, part of what observers say is an attempt to assert control over almost the whole of the body of water.
Several countries - along with Taiwan - also claim parts of the sea.
The US and its allies have carried out high-profile overflights of the sea, nearing the artificial islands, in what they say are routine "freedom of navigation" exercises in international waters.
Beijing says they are provocations and infringements of Chinese sovereignty.
In their meeting on Wednesday, Vice Foreign Minister Zheng Zeguang told Lee the weapons deal "severely goes against international law and the basic norms of international relations", adding that it "severely harms China's sovereignty and security interests".
Washington, which is bound by domestic laws to supply defence materials to Taiwan, played down the impact of the agreement.
State Department spokesman John Kirby said the deal was in keeping with long-held American policy and would not affect relations with Beijing.
"As for our relationship with China, that remains an important relationship that we're going to continue to work at," he said.
"There's no other message that needs to be taken away from this, other than we take seriously our commitment to the defence needs of Taiwan." Relations between Beijing and Taipei have warmed under current Taiwanese President Ma Ying-jeou.
China's leader Xi Jinping and Ma met for a historic summit in November, the first leaders' summit since the 1949 split.
That meeting, and the generally pro-Beijing posture of Ma's administration, has caused disquiet in Taiwan, where many people fear the growing reach of the world's second largest economy.
Taipei said the deal was a testament to its right to self-defence.
"The US pays heed to Taiwan's need to defend itself and would like to help Taiwan maintain sufficient self-defence capabilities," the island's defence ministry statement said in a statement.
Observers said the Chinese reaction was predictable bluster from Beijing.
The deal is unlikely to have a signficant impact on Sino-US relations, said Bonnie Glaser, a senior adviser for Asia at the Washington-based Center for Strategic and International Studies.
"China threatened to impose sanctions on US defence companies who were responsible for the sale the last time the US announced an arms sale to Taiwan, but they didn't follow through", she said.
She added that Beijing will likely stop short of taking steps this time for fear that Washington might retaliate with its own sanctions.
The deal includes two Perry-class Frigates, Javelin anti-tank missiles, TOW 2B anti-tank missiles, AAV-7 Amphibious Assault Vehicles and a range of other military equipment.