The United States sent two Navy ships through the Taiwan Strait on Wednesday in the third such operation this year, as the U.S. military increases the frequency of transits through the strategic waterway despite opposition from China.
The voyage risks further heightening tensions with China but will likely be viewed in self-ruled Taiwan as a sign of support from U.S. President Donald Trump's government amid growing friction between Taipei and Beijing.
"The ships' transit through the Taiwan Strait demonstrates the U.S. commitment to a free and open Indo-Pacific," U.S. Pacific Fleet said in a statement. "The U.S. Navy will continue to fly, sail and operate anywhere international law allows."
It said the passage was carried out by Stockdale destroyer and Pecos, a replenishment vessel.
Taiwan's Defense Ministry said it was a normal transit through international waters in the Taiwan Strait and that Taiwanese forces had monitored the passage of the ships.
There was no immediate reaction from China.
The latest move comes ahead of an expected meeting between Trump and Chinese President Xi Jinping this week in Argentina on the sidelines of a G20 summit.
The U.S. Navy conducted a similar mission in the strait's international waters in July, which had been the first such voyage in about a year.
The latest operation shows the U.S. Navy is increasing the pace of strait passages.
Washington has no formal ties with Taiwan, but is bound by law to help it defend itself and is the island's main source of arms. The Pentagon says Washington has sold Taiwan more than $15 billion in weaponry since 2010.
China has been ramping up pressure to assert its sovereignty over the island, which it considers a breakaway province of "one China."
Over the weekend, Taiwan's ruling pro-independence Democratic Progressive Party suffered heavy losses in mayoral and county elections to the China-friendly Kuomintang, which has been welcomed by Beijing.
Taiwan is only one of a growing number of flash points in the U.S.-China relationship, which also include a trade war, U.S. sanctions and China's increasingly muscular military posture in the South China Sea.