The “Immediate Combat Readiness Exercise” will run through Friday and forms part of Taiwan’s broader military modernization efforts to shift training toward realistic wartime scenarios and away from traditional scripted drills, the Ministry of National Defense said on Sunday.

The exercise comes as Taiwan increasingly bases portions of its military planning on the possibility that China could transform one of its frequent military operations around the island into a real attack with little warning.

According to the ministry, the drills will focus on improving the armed forces’ ability to conduct rapid transitions from peacetime to wartime conditions, while enhancing battlefield deployment, command coordination, logistical support and joint operational capabilities.

“The main objective is to train units at all levels to become familiar with combat practices and the battlefield environment during the readiness deployment phase,” the ministry said in a statement.

Officials said the exercise would involve troops operating in real-time conditions using actual equipment and terrain, reflecting Taiwan’s growing emphasis on combat-oriented training.

The announcement coincided with a new report of Chinese military activity near the island. Taiwan said 21 Chinese military aircraft, including J-16 fighter jets, KJ-500 airborne early warning aircraft and Y-20 aerial refueling planes, were detected operating near Taiwan on Sunday.

Nineteen of the aircraft entered airspace to Taiwan’s southwest and proceeded into the Western Pacific for what Taipei described as long-distance training missions over open seas.

Taiwan’s military said it monitored the activity and deployed forces to respond, using what it described as appropriate measures.

China, which views Taiwan as part of its territory despite the objections of the government in Taipei, has increased military operations around the island in recent years, regularly sending warships and aircraft into nearby waters and airspace.

Taiwan has responded by accelerating defense reforms, expanding reserve-force training and increasing the realism of military exercises designed to prepare for a potential cross-strait conflict.

Earlier this month, Taiwan conducted live-fire tests of its newly acquired U.S.-made High Mobility Artillery Rocket System (HIMARS), a weapon platform that has gained prominence through its battlefield use in UkraineTaiwan’s annual Han Kuang military exercises, the island’s largest war games, are expected to take place in August.

Taiwan’s Ministry of National Defense said it detected 21 Chinese military aircraft, including J-16 fighter jets and unmanned aerial vehicles, operating around Taiwan on Monday alongside Chinese naval vessels participating in what Beijing describes as a joint combat readiness patrol.

The patrol marked the second such operation within a week and came as Taiwan remains alert to potential shifts in Chinese military behavior following discussions on Taiwan between Chinese President Xi Jinping and U.S. President Donald Trump during Trump’s recent visit to Beijing.

China claims Taiwan as part of its territory and has steadily increased military pressure on the island through frequent deployments of warships and military aircraft. Taiwan’s government rejects Beijing’s sovereignty claims and maintains that only the island’s people can determine their future.

According to Taiwan’s defense ministry, the Chinese aircraft and naval vessels operated around multiple sectors of the island before the patrol concluded. Taipei responded by dispatching ships and combat aircraft to monitor the movements and maintain surveillance.

The ministry also released images captured by Taiwanese forces, including photographs from an F-16 fighter showing two Chinese aircraft flying near a Y-20 aerial refueling tanker. Additional images showed the Chinese guided-missile destroyer Yinchuan and a Taiwanese sailor observing the vessel through binoculars.

Speaking in Taipei on Tuesday, Pan Chun-kuang of the defense ministry’s intelligence department said the latest patrol had ended but stressed that Taiwan continued to monitor Chinese military activities in surrounding waters and airspace.

Pan said Taiwan was closely tracking the movements of China’s aircraft carrier Liaoning in the Western Pacific and would provide additional information on Chinese deployments when necessary.

The latest operation followed a similar Chinese readiness patrol conducted last Tuesday, one day before Taiwan President Lai Ching-te marked the second anniversary of his administration. Beijing has repeatedly labeled Lai a separatist and has rejected his offers for dialogue.

Military activity has also extended beyond the Taiwan Strait. Over the weekend, Taiwan’s coast guard reported an encounter with a Chinese coast guard vessel near the Taiwan-controlled Pratas Islands, a strategically important outpost in the northern reaches of the South China Sea.

Separately, Taiwan National Security Council Secretary-General Joseph Wu said on social media that approximately 100 Chinese vessels were operating within the so-called first island chain, a strategic maritime corridor stretching from Japan through Taiwan to the Philippines.

China’s Ministry of National Defense did not immediately comment on Taiwan’s account of the patrol.

The increased tempo of Chinese military operations reflects Beijing’s continued effort to assert its claims over Taiwan while testing the island’s defensive readiness and signaling its opposition to any moves it perceives as supporting Taiwanese sovereignty.

The Japanese destroyer sailed through the strait from early morning to late afternoon, according to a statement by a Chinese military spokesperson, who said naval and air forces were deployed to observe the vessel throughout its passage.

Japan’s Self-Defense Forces declined to comment on the transit. The passage comes against the backdrop of heightened regional tensions over Taiwan, which claims as its territory despite opposition from ’s government.

Beijing considers the Taiwan issue a core national interest and frequently characterizes it as a “red line” in diplomatic relations. It also asserts sovereignty over the strait, a key international shipping route, and has responded strongly to foreign naval movements in the area.

China’s foreign ministry spokesperson said at a press briefing that the transit represented a “display of force” and accused Japan of compounding earlier tensions with what he described as “mistakes upon mistakes.” He added that China had lodged formal diplomatic protests with Tokyo.

Relations between the two countries have deteriorated in recent months, particularly after remarks by Japanese Prime Minister suggesting that a potential Chinese attack on Taiwan could trigger a Japanese military response.

China’s military had previously tracked a foreign naval transit through the strait in February, when an Australian warship sailed the same route, according to state-backed media reports. The latest incident underscores persistent friction over freedom of navigation and sovereignty claims in one of Asia’s most strategically sensitive waterways.