China has sent dozens of warplanes, including fighter jets and bombers, toward Taiwan, the island’s defense ministry said on Saturday, marking a forceful display days before the democracy plans to hold military exercises aimed at fending off a possible invasion.

Taiwan is due to hold its annual Han Kuang exercise next week, during which its military will conduct combat readiness exercises to prevent an invasion. It will also carry out the annual Wan’an exercises aimed at preparing civilians for natural disasters and practicing evacuations in the event of an air raid.

The Chinese People’s Liberation Army sent 37 planes and seven navy ships around Taiwan between 6 a.m. Friday and 6 a.m. Saturday, the ministry said in a statement.

Among them were J-10 and J-16 fighters and H-6 bombers, and 22 of the detected fighter jets crossed the median line of the Taiwan Strait, an unofficial boundary that had been considered a buffer between the island and the mainland, or entered Taiwan’s air defense identification zone near its southern part, according to the statement.

Taiwan and China separated in 1949 after a civil war that ended with the ruling Communist Party in control of the mainland. The island has never been part of the People’s Republic of China, but Beijing says it must unite with the mainland.

In recent years, China has shown its distaste for political activities in Taiwan by increasing the number of military aircraft sent to the island.

China held huge military exercises in response to former US House Speaker Nancy Pelosi’s visit to Taiwan in August. She fired missiles at the island in a significant escalation that disrupted trade routes in the Taiwan Strait and forced planes to divert flights.

In April, the PLA also conducted large-scale air and sea combat readiness drills around the island in response to Taiwan President Tsai Ing-wen’s meeting with current US House Speaker Kevin McCarthy.