Japan Should Help Sink China’s Invasion Fleet

U.S. President Donald Trump wants U.S. allies to step up. Japanese Prime Minister Sanae Takaichi, who is in Washington this week, could answer with a strategic proposal: If China moves to invade Taiwan, Japan will help sink Beijing’s landing ships before they reach the island.

This wouldn’t be charity toward Taipei. It would be a commitment to the U.S.-Japan alliance—and to Japan’s own survival.

Takaichi put this issue front and center in November, when she said that a Chinese blockade of Taiwan might constitute a threat to Japan’s “survival.” She did not explicitly mention military force, but this was implied: Under security laws passed in 2015, Japan can use force in a “survival-threatening situation,” even when the country is not under direct attack.

Takaichi’s statement was not a war pledge. She never vowed that Japan would intervene to defend Taiwan nor suggested that Tokyo would take unilateral action. Still, she got Beijing’s attention. Chinese Foreign Minister Wang Yi called her remarks “shocking,” and Beijing’s ambassador to the United Nations called them a “threat of force” violating international law. The Chinese consul general in Osaka even threatened her with beheading. China has since canceled airline flights to Japan and banned exports, including critical minerals.

Takaichi’s comments track with the evolution of Japanese thinking on defense. Although Japan has maintained an exclusively self-defense doctrine since 1954, the 2015 security laws enable the country’s Self-Defense Forces to protect U.S. forces under attack if the prime minister declares a survival-threatening situation. Over the past decade, prominent politicians—including late Prime Minister Shinzo Abe—began publicly defining a Taiwan invasion as a threat to Japan’s survival.

The strategic logic is straightforward. If Taiwan falls, Japan faces a drastically different geopolitical reality. A victorious China would be an immediate neighbor. Worse, should a Chinese victory mark a U.S. defeat, Japan might no longer have a credible ally upon which to rely, leaving it vulnerable to an emboldened Beijing.

A Japanese commitment on Taiwan should be welcomed by the White House. The U.S. military needs help to defeat a Chinese invasion of Taiwan.

The most rigorous public war game of such a scenario was conducted in 2023 at the Center for Strategic and International Studies (CSIS). Called “The First Battle of the Next War,” it ran through 24 iterations exploring a hypothetical 2026 U.S.-China conflict over Taiwan. A critical early phase is always the transit of a large-scale Chinese invasion fleet across 100 miles of water. One consistent finding from CSIS: The United States runs out of long-range anti-ship missiles within the first week.

As experts on Chinese and Japanese forces who participate in similar war games, we’re often asked what the U.S. side could do differently. The answer is easy: Don’t fight alone.

Japan is already building the counterstrike capabilities needed. Tokyo has signed a $2.4 billion contract for 400 Tomahawk cruise missiles, including anti-ship variants. Its fleet of F-35 fighter jets—eventually to number around 150—will carry Norwegian-made Joint Strike Missiles designed to sink ships. Japan is also developing its own anti-ship cruise missile, called Type 12 and tested at ranges exceeding 1,000 kilometers, among other missiles that could target China and its invasion forces.

These growing capabilities explain why Beijing is incensed at Takaichi. Any signal that Japan may be a player in a Taiwan scenario complicates Chinese military planning and raises the risks of an invasion strategy for Chinese leader Xi Jinping. Japan’s Self-Defense Forces would be a significant force multiplier for Taiwan’s defenders, helping repel an invasion at its most vulnerable moment: before it reaches Taiwanese shores.

Japan’s commitment should be made, at least at first, in private conversations with Trump and his advisors. Even if this monumental step is not public, Beijing is very likely to pick up on it, given Chinese attentiveness to policy deliberations in both capitals, especially regarding deterrence against a Chinese invasion.

Giving a clear signal of Japanese readiness to strike a Chinese invasion force would demand extraordinary political courage from Tokyo, but Takaichi has already shown she has it. Washington can help. Private assurances that the United States will defend Taiwan would be a prerequisite for Tokyo to even consider such a proposal. Accelerating the delivery of U.S. weapons and co-producing key munitions would ensure a robust Japanese stockpile. Joint U.S.-Japanese contingency planning and realistic exercises would prepare the alliance for Japan’s first potential combat since 1945.

None of this would be easy. Any political commitment to strike China, even a private one, could be open to interpretation as enabling offensive military action by Japan and would mark a consequential shift in Japan’s security policy. Operationally, targeting moving vessels through China’s air defenses demands capabilities that Japan is still developing. And Washington and Tokyo will have to coordinate how to message their commitment to China.

Yet the alternative is worse. A China that conquers Taiwan could interdict Japan’s sea lanes at will and project power across the western Pacific, particularly if the U.S. presence in the region is diminished. A future Japanese prime minister who wakes to find a Chinese flag flying over Taipei 101 would surely ask why Tokyo failed to act while it still could.