War-game simulations of a full-scale Chinese invasion of Taiwan predict heavy casualties for all possible parties involved, including the U.S. and Japan.

The Center for Strategic and International Studies (CSIS) has run simulations of a Chinese invasion of Taiwan in 2026 exactly 24 times, relying on historical data and operational research. The simulation events are included in an extensive report, The Hill writes.

In most scenarios, the alliance between the U.S., Japan and Taiwan defeated China after three to four weeks of fighting, but with the loss of dozens of ships, hundreds of planes and tens of thousands of soldiers.

Mark Cancian, senior adviser to the CSIS International Security Program and author of the report, told The Hill that the main takeaway from the simulation is that Taiwan can persist as an independent state.

In the report, Cancian recommended policies and efforts to deter a future invasion, noting that even if war is seen as risky for China, the country could still consider direct conflict.

The simulations are based on historical information and ground combat data during the landing invasion, as well as presumptive models of missile attacks based on the size of the warheads and the area they would cover on impact. The games include a wide range of scenarios, taking into account when China performs better than expected or worse.

Although most scenarios are dominated by the U.S. and Taiwan, there are some conditions for success, including that Taiwan must hold the defense and U.S. forces must have access to bases in Japan.

The model predicts 19 scenarios of Japanese involvement in the conflict. Japan has been ambivalent about defending Taiwan, but Prime Minister Fumio Kishida announced last year a historic abandonment of a strategy focused solely on defense and a significant increase in its annual defense spending.

Although China has a greater presence in the South China Sea, the U.S. still has stronger military forces around the world, and there must be some pessimistic conditions for military defeat in war.

Nevertheless, as the simulation showed, any direct conflict between China and the U.S. would devastate Taiwan and possibly weaken the U.S. on the world stage.

The simulation had some limitations, including an estimate of China's military level in four years. According to the Defense Department, China aims to build a "world-class" military within the next two decades and intends to quadruple its nuclear arsenal over the next 13 years.

The CSIS also did not model a nuclear weapons scenario, which would mean a completely different type of warfare or the possibility of a Chinese blockade of the island.

Another possible scenario is that Taipei would quickly surrender to China and offer little resistance, or the war would last longer than three to four weeks, meaning more casualties.