The US Navy challenged China's excessive claims to the South China Sea on Nov. 26, 2018, by sending a warship past a Chinese military outpost in the disputed waterway.

The Ticonderoga-class guided-missile cruiser USS Chancellorsville "sailed near the Paracel Islands to challenge excessive maritime claims and preserve access to the waterways as governed by international law," US Navy Cmdr. Nathan Christensen, a spokesman for US Pacific Fleet, told CNN Nov. 29, 2018, in a statement that was also provided to Business Insider.

A Chinese vessel reportedly shadowed the US Navy warship during the operation.


"US Forces operate in the Indo-Pacific region on a daily basis, including the South China Sea," Christensen added. "All operations are designed in accordance with international law and demonstrate that the United States will fly, sail and operate wherever international law allows."

"FONOPs challenge excessive maritime claims and demonstrate our commitment to uphold the rights, freedoms, and uses of the sea and airspace guaranteed to all nations under international law."

The Ticonderoga-class guided missile cruiser USS Chancellorsville.

Beijing responded with a formal diplomatic protest, CNN reported, citing multiple US officials.

China claims the vast majority of the South China Sea, and while those claims were discredited by an international arbitration tribunal two years ago, the Chinese military has continued to bolster its presence in the region through the deployment of jamming technology, anti-ship missiles, and surface-to-air missiles.

Two days after the latest FONOP, the US Navy aggravated China again by sending a destroyer and an oiler through the Taiwan Strait. The destroyer USS Stockdale and the underway replenishment oiler USNS Pecos pushed through the closely-watched strait Nov. 28, 2018, drawing some criticism from Beijing.

"We urge the United States to ... cautiously and appropriately handle the Taiwan issue and avoid damaging the peace and stability of the Taiwan Strait and China-US relations," Chinese Ministry of Foreign Affairs spokesman Geng Shuang said Nov. 29, 2018.

"The ships' transit through the Taiwan Strait demonstrates the U.S. commitment to a free and open Indo-Pacific," Pacific Fleet told Business Insider Nov. 28, 2018.

The US military has been increasingly active, both at sea and in the air, in areas China considers key national interests, as tensions between Washington and Beijing have been rising over the past year.

In addition to US Navy FONOPs, the US Air Force has regularly sent B-52 bombers into the South China Sea, occasionally drawing Beijing's ire.

While most incidents are uneventful, the US and Chinese navies had a close call in late September, when a Chinese warship challenged a US Navy destroyer, forcing it off course through aggressive maneuvers that US officials called dangerous and unprofessional.

This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.