The United States will sell anti-ship missiles to Taiwan in a $90 million deal, ending what analysts said had been an arms sale freeze designed to ease tension between Beijing and Taipei.
Taiwan will buy 60 Harpoon Air Launch missiles made by McDonnell Douglas Corp, the US Department of Defense said. The surface-skimming missiles can sink ocean-going warships.
"Due to rising tension in the Taiwan Strait, the US had postponed the decision," said Andrew Yang, secretary-general with the Taiwan think-tank China Council of Advanced Policy Studies.
"It is a good sign, a positive gesture that the US is taking some actions in regard to Taiwan's defence requests."
Washington is still sitting on a $12 billion package of additional weaponry sought by Taiwan.
China has claimed sovereignty over Taiwan since 1949, when Mao Zedong's Communists won the Chinese civil war and Chiang Kai-shek's Nationalists (KMT) fled to the island. Beijing has vowed to bring Taiwan under its rule, by force if necessary.
The United States switched diplomatic recognition from Taipei to Beijing in 1979, recognising "one China", but remains Taiwan's biggest ally and is obliged by the Taiwan Relations Act to help the island defend itself.
Last month reports in local and international media cited a top US military official as saying the United States had frozen new arms sales to Taiwan.
"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 government said in a statement on the Harpoon missiles last year.
But US officials later quit selling weapons to Taiwan under the island's former President Chen Shui-bian, fearing Chen would provoke Beijing, defence analysts said.
Current Taiwan President Ma Ying-jeou has reached out to China since taking office on May 20, making landmark progress in trade and travel. But his defence minister has said China remains a military threat.