A U.S. Navy destroyer sailed through the increasingly militarized Taiwan Strait on Thursday after Chinese forces stepped up their own warplane and warship activities around the island this week.

The guided-missile destroyer USS Ralph Johnson made a routine transit through the strait, which is 100 miles wide, in accordance with international law, the Navy’s 7th Fleet said in an online statement. The warship transit was the first by an American naval vessel in three months and the fourth operation of its kind this year.

The Navy had been conducting near-monthly Taiwan Strait passages in an effort to counter expansive Chinese claims that the waterway is Beijing’s sovereign maritime territory.

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The last U.S. warship to pass through the waterway was the destroyer USS Halsey on May 8. A P-8 maritime patrol aircraft also flew over the Taiwan Strait in May. Two Navy warship passages also took place on March 5 and Jan. 24.

China’s military said it watched and warned the ship during its passage.

An eastern theater command spokesman said the Chinese military “organized naval and air forces” to monitor the Ralph Johnson’s trip. Col. Xi Li, the spokesman, said on the command’s social media account that the passage was “publicly hyped up” by the U.S.

“The theater troops are always on high alert and resolutely defend national sovereignty and security and regional peace and stability,” Col. Xi said.

The Navy destroyer conducted the operation in line with international law and sailed through a corridor that is beyond the territorial sea of both China and Taiwan, the 7th Fleet statement said.

“Ralph Johnson’s transit through the Taiwan Strait demonstrates the United States’ commitment to upholding freedom of navigation for all nations as a principle,” the statement said. “No member of the international community should be intimidated or coerced into giving up their rights and freedoms.”

Chinese military forces, meanwhile, stepped up military flights and naval operations near Taiwan over the past several days, according to Taiwan’s Defense Ministry. On Friday, 27 Chinese military aircraft, including J-16 fighters and KJ-500 airborne control aircraft, were detected. A total of 23 aircraft crossed the median line down the Taiwan Strait and flew into the island’s air defense zone, the Taiwanese ministry said on its X account.

The aircraft was conducting air-sea joint training. Taiwanese armed forces monitored and responded to the incursions.

A day earlier, a total of 41 Chinese military aircraft and seven warships conducted operations around Taiwan, the ministry said, with 32 aircraft crossing the median line.

White House national security adviser Jake Sullivan is expected to raise China’s pressure on Taiwan in talks in Beijing next week.

“I expect in these conversations next week we’re going to raise concern about the PRC’s increased military, diplomatic, and economic pressure against Taiwan,” a senior administration official told reporters, using the abbreviation for People’s Republic of China. “These activities are destabilizing and risk escalation.”

China’s military has stepped up provocative aerial and maritime activities around Taiwan to protest the August 2022 visit to Taiwan by then-House Speaker Nancy Pelosi. The Chinese military forces that cross the median line are upsetting a fragile status quo that has kept the peace between China and Taiwan for decades.

Secretary of State Antony Blinken said in 2023 that the United States opposes any unilateral changes in the status quo by either China or Taiwan. The Institute for the Study of War, a leading think tank, said the Chinese military conducted a 30-hour patrol of the Taiwan Strait that ended Wednesday in a possible bid to extend its legal claims over the waterway.

“The increase in maritime traffic in the Taiwan Strait risks accidents and other incidents involving PRC and [Taiwanese] vessels, which the PRC may use as a pretext to expand the scope of its law enforcement activities against Taiwan,” the institute said in a report.

Meanwhile, two German warships are in the region and poised to conduct a passage through the strait, according to Reuters. The naval task force is awaiting orders before conducting the first German navy passage of the strait in decades.

“The decision has not been taken yet,” Rear Adm. Axel Schulz, the commander of the naval group, told Reuters. “We are showing our flag here to demonstrate that we stand by our partners and friends, our commitment to the rules-based order, the peaceful solution of territorial conflicts and free and secure shipping lanes.”

The planned German warship transit is part of the Biden administration’s efforts to internationalize patrols in the Taiwan Strait to preserve freedom of navigation there. Canadian and French warships have conducted Taiwan Strait transits in recent months.

China’s Foreign Ministry urged Germany not to conduct the passage and asserted that the Taiwan issue is an internal affair.

“China has always been opposed to the undermining of China’s territorial sovereignty and security under the guise of freedom of navigation,” ministry spokesperson Mao Ning told reporters in Beijing.

The Navy destroyer passage and potential German warship passage comes as tensions remain high in the South China Sea. A Chinese coast guard ship, for example, rammed a Philippine coast guard ship near a disputed shoal Aug. 19.