The government of Taiwan announced a new live-fire drill next month in Taiping Island, a territory disputed by China and Vietnam, the South China Morning Post reported on Tuesday.

Taiwan’s drill shortly follows the passage of U.S. warships through international waters in the region, angering China. The drill may also incense neighboring Vietnam, the Post suggests, as that country claims the relevant part of the Spratly Islands. Taiping is the largest island in the Spratly chain.

China typically disregards Taiwan’s claims in the South China Sea, instead using all manifestations of sovereignty on Taipei’s part as evidence of China’s sovereignty over the region. China claims all of Taiwan as a rogue province.

China has expanded its presence in the South China Sea to include illegal constructions on land belonging to Taiwan and Vietnam. Beijing also claims parts of Indonesia, Malaysia, Brunei, and the Philippines.

The drills announced this week, according to the Post, are scheduled for November 21-23 and will feature 40mm grenade machine guns. Taiwan’s Coast Guard told the Post that the event will be a “routine shooting practice, which we have held for years.” The Coast Guard added that Vietnam and other neighboring countries were aware of the drill and Taipei had no reason to believe they opposed it.

The announcement comes a day after the U.S. Navy confirmed the passage of two of its warships through the Taiwan Strait, technically international waters.

“The ships’ transit through the Taiwan Strait demonstrates the U.S. commitment to a free and open Indo-Pacific,” spokesman Navy Cmdr. Nate Christensen said, adding, “The U.S. Navy will continue to fly, sail and operate anywhere international law allows.” The transit was the first of its kind publicly announced since 2007.

“The Taiwan issue concerns the sovereignty and territorial integrity of China. It is the most important and sensitive issue amid China-US relations,” Chinese Foreign Ministry spokeswoman Hua Chunying said on Tuesday in response to the report. “We urge the US to observe the one-China principle and the stipulations of the three China-US joint communiqués and prudently and properly handle Taiwan-related issues so as to avoid undermining China-US relations and the peace and stability across the Taiwan Straits.”

Prior to the U.S. passage, Taiwan announced last week plans to expand its military technology arsenal and replace infantry in the Taiwan Straits with a “major automation initiative,” funded in part with over $23 million allocated to buy “six indigenous automated close-range defense systems and two joint-forces management systems.” The control center for this new automated defense and surveillance system is expected to be built on Taiping, known also as Itu Aba.

The government of Taiwanese President Tsai Ing-wen has also planned a visit by several Taiwanese military officials to the United States this month to request expanded military sales to the country. Taiwan is reportedly particularly interested in buying military aircraft to protect from a mainland invasion.

Under the Trump administration, Washington has proven more open to Taiwanese requests for support. Last month, the State Department confirmed the sale of $330 million in spare aircraft parts to Taipei.

“This proposed sale will contribute to the foreign policy and national security of the United States by helping to improve the security and defensive capability of the recipient,” the State Department said in a press release.

Taiwan itself has changed to a more proactive stance regarding seeking out international alliances, however, under President Tsai. Tsai engaged in an unprecendented phone call with President Trump in 2016 to congratulate him on his election victory, triggering a stern rebuke from Japan. She has also undertaken several visits to Latin America, traditionally one of the most Taiwan-friendly regions in the world, and made a historic visit to the Johnson Space Center in Houston in August.

In a speech commemorating Taiwan’s founding day this month, Tsai urged the international community to support Taiwan’s sovereignty, challenging China directly.

“For some time now, China’s unilateral diplomatic offensive and military coercion have not only harmed cross-strait relations. They have also seriously challenged the status quo of peace and stability in the Taiwan Strait,” she said. “The best way to defend Taiwan is to make it indispensable and irreplaceable to the world.”

“The people of Taiwan will never accept any attempt by external forces to unilaterally change the cross-strait status quo. And the international community will never approve of and support the violation of universal values,” she concluded.

The shooting drills next month are far from the first such exercises appearing to prepare for a Chinese invasion. Last week, Taiwan simulated a Chinese attack in the direction of the East China Sea, training to attack the nation’s only aircraft carrier, the Liaoning.

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