US President Donald Trump declined to approve $400 million in military aid to Taiwan in recent months while negotiating on trade and a potential summit with Beijing, the Washington Post reported Thursday.
The decision would mark a sharp departure from US policy toward the democratic island, which faces a constant threat of invasion by China.
A White House official told the Post that the aid package decision was not yet final.
Trump and his Chinese counterpart Xi Jinping are set to speak Friday, their second call since the 79-year-old Republican returned to the White House. The telephone talks come as the two sides seek a compromise on tariffs and a deal on video-sharing app TikTok.
While the United States stopped recognizing Taiwan in the late 1970s in favor of China, Washington has remained Taipei's most important backer and biggest supplier of military aid.
Under former president Joe Biden, Washington approved more than $2 billion in military aid packages for Taiwan. But Trump "does not support sending weapons without payment, a preference also on display with Ukraine," the Post noted.
It said that US and Taiwanese defense officials met in Anchorage, Alaska in August and discussed a package of weapons sales "which could total in the billions of dollars," including drones, missiles and sensors to monitor the island's coastline.
Since Trump returned to the White House in January, there have been growing jitters in Taipei over the strength of the Taiwan-US relationship and Washington's willingness to defend the island if China were to attack.
Visiting Taiwan in late August, the head of the US Senate armed services committee said he was determined the United States and Taiwan remain "the best of friends."
"It is our determination and our intention that Taiwan remain free and make its own decisions," Republican Senator Roger Wicker said after talks with Taiwanese President Lai Ching-te.
"Part of maintaining the freedoms that we have is enhanced cooperation militarily, enhanced cooperation with our defense industrial base, making the best use of those funds."