Amid intensifying Chinese military activities, the Self-Defense Forces have conducted exercises and deployed units near Taiwan to show off their capabilities to China.

The operations are based on “flexible deterrent options” (FDO), which aim to deter the escalation of military tensions with an adversary by demonstrating one’s strength in response.

The SDF has selected waters and airspace close to Taiwan, areas where it had not conducted drills, for FDO operations.

On Oct. 3, the Maritime SDF destroyer Sawagiri and the minesweeper tender Uraga conducted a mine warfare drill in international waters south of the Sakishima Islands in Okinawa Prefecture, near Taiwan.

It was likely the first time mine warfare training had been conducted in that sea area, according to Defense Ministry officials.

A mine warfare drill involves laying and recovering mines or dummy mines to obstruct enemy shipping lanes.

Until now, such exercises had typically been conducted over one to two weeks in locations such as Mutsu Bay in Aomori Prefecture and the Hyuganada Sea off Miyazaki Prefecture.

This time, the aim was not to improve proficiency but simply to confirm procedures up to the point of releasing the mines, such as spacing for mine deployment and coordination among crew members.

“It was only a one-day drill and lacked practicality, but it was designed to show China what we can do as part of FDO,” a senior Defense Ministry official said.

Within the ministry, planning for this exercise had been under way for about a year.

During an internal meeting, Yoshihide Yoshida, then chief of staff of the Joint Staff, referred to the training area as “Tennozan,” meaning that it could become a decisive chokepoint in the event of a Taiwan contingency.

Laying mines in this area to hinder Chinese naval movements during such a crisis is one option being considered within the ministry.

In June, the Chinese Navy deployed its aircraft carriers, the Liaoning and the Shandong, to the Pacific Ocean near Japan. It was the first time two Chinese carriers operated simultaneously in the area.

According to Defense Ministry sources, immediately after the Liaoning set sail, the SDF conducted a drill involving F-2 and F-15 fighter jets in the same area, which falls within Japan’s exclusive economic zone near the Senkaku Islands in Okinawa Prefecture

The exercise included procedures simulating attacks on vessels because the F-2 can carry anti-ship missiles.

A senior ministry official described the drill as “a countermeasure against Chinese carrier movements.”

It was deliberately conducted in airspace monitored by the Chinese military, where the SDF does not normally train, as part of FDO.

Based on a training plan drawn up by the uniformed staff, Kazuo Masuda, then vice defense minister, led discussions on what type of training, conducted in which area and at what time, would best convey a “counter-message” to China.

The passage of MSDF destroyers through the Taiwan Strait is also cited as a form of FDO.

In August last year, a Chinese military aircraft violated Japanese airspace for the first time. As a countermeasure, an MSDF destroyer for the first time transited the Taiwan Strait the following month alongside vessels from Australia and New Zealand. 

MSDF destroyers also made solo transits in February and June.

“We will likely continue to seize opportunities to make such transits,” a government source said.

FDO is a concept originating in the United States.

A prime example occurred during a Taiwan Strait crisis in 1996, when the United States dispatched two aircraft carriers near Taiwan to deter China.

“Even routine training can provide deterrence if we choose the correct timing and location,” a senior Defense Ministry official said.

Japan first incorporated FDO into the Guidelines for Japan-U.S. Defense Cooperation in 2015, aiming to demonstrate strong resolve and coordination through joint exercises.

Subsequently, FDO was spelled out as a deterrence in the National Defense Program Guidelines in 2018 and the National Defense Strategy in 2022.

The National Defense Strategy emphasizes the need to strengthen FDO drills and exercises with allies and partners to continuously demonstrate the will and capability to deter unilateral changes to the status quo by force or coercion and influence the adversary’s behavior.

A decade after FDO was officially adopted in Japan, it has become widely recognized within the government as “a guiding principle when devising strategy and training content,” according to a government source.

The Defense Ministry sometimes coordinates with the National Security Secretariat and the Foreign Ministry to assess diplomatic implications to neighboring countries before deciding whether to conduct exercises.

FDO carries the risks of accidental clashes and escalation, although it can effectively signal intent.

“Precisely because missions based on FDO and other strategies increasingly take place in waters close to Chinese territorial seas, even a minor mistake could be fatal,” a government source said.