US Defense Secretary Lloyd Austin on Saturday blasted China's "provocative, destabilizing" military activity near Taiwan, as well as Beijing's growing aggression across the wider Asia-Pacific region.
Tensions between Washington and Beijing are soaring over democratic, self-ruled Taiwan, which China views as its territory and has vowed to seize one day, by force if necessary.
Beijing has conducted dozens of incursions into Taiwan's air defense zone this year, and on Friday, Defense Minister Wei Fenghe warned Austin that China was prepared to go to war if the island declares independence.
In an address to the Shangri-La Dialogue security summit in Singapore, Austin took aim at Beijing's "growing coercion" towards Taiwan, a day after holding his first face-to-face talks with Wei.
"We've witnessed a steady increase in provocative and destabilizing military activity near Taiwan," he told the forum, which is attended by defense ministers from Asia and around the world.
"That includes (Chinese military) aircraft flying near Taiwan in record numbers in recent months, and nearly on a daily basis," AFP quoted him as saying.
"We categorically oppose any unilateral changes to the status quo from either side," he added.
But he also stressed the importance of "fully open lines of communication with China's defense leaders" in avoiding miscalculations.
"These are deeply, deeply important conversations."
On Friday, Wei had warned Austin that "if anyone dares to split Taiwan from China, the Chinese army will definitely not hesitate to start a war no matter the cost", according to Chinese officials.
He also vowed that Beijing would "smash to smithereens any 'Taiwan independence' plot and resolutely uphold the unification of the motherland", according to the Chinese defense ministry.