US warships sail through the closely-watched Taiwan Strait, keeping pressure on Beijing

MC3 Patrick Dionne/US Navy

The USS McCampbell, pictured in 2016, transited through Chinese claimed waters Monday.

• The US Navy sent the destroyer USS McCampbell and replenishment oiler USNS Walter S. Diehl through the Taiwan Strait Thursday.
• It is the fourth time the Navy has publicly admitted to sending surface combatants through the closely-watched strait since the US restarted the practice last summer.
• It comes at a sensitive time in US-China relations, and is likely to draw criticism from Beijing, which has previously bristled at US military activity in the region.

US Navy warships sailed through the Taiwan Strait Thursday, in an apparent challenge to Beijing.

The Areligh Burke-class guided-missile destroyer USS McCampbell and the Henry J. Kaiser-class fleet replenishment oiler USNS Walter S. Diehl conducted a Taiwan Strait transit, demonstrating "the US commitment to a free and open Indo-Pacific," US Pacific Fleet spokesman Lt. Cmdr. Tim Gorman told CNN.

"The US Navy will continue to fly, sail and operate anywhere international law allows," he added.

The rhetoric in his statement is consistent with that used for freedom-of-navigation operations (FONOPs) and bomber overflights in the South China Sea, actions that tend to agitate the Chinese government.

After the USS McCampbell conducted a FONOP earlier this month, Chinese media responded with a warning that its military had deployed DF-26 missiles capable of sinking enemy ships in the South China Sea.

Read More: The US Navy sent the destroyer USS McCampbell and replenishment oiler USNS Walter S. Diehl through the Taiwan Strait

While Taiwan Strait transits by US warships occurred infrequently in the past, the US has made these maneuvers routine in the past year, which has been characterized by rising tension between Washington and Beijing.

The US Navy sent the destroyer USS Stockdale and the replenishment oiler USNS Pecos through the strait in November, just a few weeks after the destroyer USS Curtis Wilbur and the cruiser USS Antietam did the same in October.

Read More: US Navy warships just sailed the Taiwan Strait in a power play ahead of Trump's meeting with the Chinese president

The destroyers USS Mustin and USS Benfold sailed the strait between mainland China and Taiwan for the first time last year in July.

The Chinese government views Taiwan, a self-ruled democratic territory, as a renegade province, and is deeply concerned about foreign interference, particularly US military support.

Beijing feels it may embolden pro-independence forces. In a recent speech, Chinese President Xi Jinping made it clear that forceful reunification remains on the table.

A new Defense Intelligence Agency assessment of China's military might explains: "Beijing's longstanding interest to eventually compel Taiwan's reunification with the mainland and deter any attempt by Taiwan to declare independence has served as the primary driver for China's military modernization."

"Beijing's anticipation that foreign forces would intervene in a Taiwan scenario led the [Chinese military] to develop a range of systems to deter and deny foreign regional force projection."

In a recent meeting with US Adm. John Richardson, Chinese Gen. Li Zuocheng asserted: "If anyone wants to separate Taiwan from China, the Chinese military will safeguard the national unity at all costs so as to protect China's sovereignty and territorial integrity," according to the South China Morning Post.

Richardson said in Japan that the Taiwan Strait is an international waterway, and left the door open for the US to send an aircraft carrier through if necessary.

Read More: China warned the US to steer clear of Taiwan, but the US Navy says it could send an aircraft carrier through the strait if it wanted

China sent military aircraft, specifically a Sukhoi Su-30 and a Shaanxi Y-8 transport plane, flying past Taiwan Tuesday, causing the Taiwanese military to scramble aircraft and surveillance ships in response. China regularly conducts encirclement drills around Taiwan.