They came near to the disputed Paracel Islands in the South China Sea - prompting a swoop by Chinese warships and aircraft.
The destroyer USS Higgins and the USS Antietam cruiser came near to the disputed Paracel Islands in the South China Sea, Reuters reported, citing an anonymous U.S. official. The US has been sending its vessels and airplanes to carry out patrol missions in the disputed area, repeatedly causing outcry from Beijing.
Though similar operations are routine, and this one had been planned months ago, it came at a crucial time: days earlier, the Pentagon uninvited China from a US-hosted naval drill.
US President Trump recently announced that the upcoming summit between the US and North Korea was canceled due to Pyongyang's "aggressive rhetoric".
RIMPAC enabled the armed forces of the world's two largest economies to directly engage with each other.
China's Defence Ministry said the United States had "ignored the facts and hyped up the so-called "militarisation" of the South China Sea", using it as an excuse to uninvite China.
The US military did not immediately comment on the operation, but said US forces operate in the region on a daily basis, Reuters said.
In March, a U.S. Navy destroyer carried out a "freedom of navigation" operation close to Mischief Reef in the Spratly Islands.
"We conduct routine and regular Freedom of Navigation Operations (FONOPs), as we have done in the past and will continue to do in the future", a representative of the US Pacific Fleet said.
In a separate statement, China's foreign ministry urged Washington to stop such actions.
China has been deploying serious military power to the region - including constructing manmade islands bristling with missiles.
Chinese officials have accused Washington of viewing their country in suspicious, "Cold War" terms.
It added that its presence in the South China Sea - which is disputed by Brunei, Malaysia, the Philippines, Taiwan and Vietnam - was legitimate, and accused the USA of holding Cold War-style suspicions.