Japan has not engaged in war since World War II, maintaining a pacifist stance under its post-war constitution. However, rising tensions in East Asia—partly due to China’s military activities near Taiwan, North Korea’s missile threats and territorial disputes—are increasing security concerns for Japan and its allies. But what happens if Japan is attacked in an act of war?
In the event of a military emergency, foreign residents in Japan might want to know evacuation procedures and potential outcomes. This article is an overview of the general procedures foreign residents would follow during a military emergency in Japan, based on information from official sources and simulations.
The Immediate Response

Japan’s Article 9 renounces war, but legal reinterpretations allow self-defense and counterattacks if Japan or its allies are under attack. The 2014 security shift enabled collective self-defense, meaning Japan can retaliate if an attack threatens its survival. In 2022, Japan expanded its military strategy by acquiring counterstrike capabilities, allowing it to hit enemy bases if an attack is imminent.
However, Japan cannot wage offensive war and must follow strict self-defense conditions. If an attack occurred in Japan, the government would likely declare a state of emergency and activate civil defense measures. These measures would involve ordering evacuations, enforcing shelter directives, and mobilizing the military. Authorities could impose restrictions on infrastructure, transportation, and communications. Law enforcement and emergency services would enforce curfews, maintain order, and assist with evacuation efforts.
In the event of a military emergency, intelligence agencies would actively monitor threats. Initially, they might withhold details to prevent public panic. Once confirming an attack, the government would declare a national emergency, mobilize the JSDF, and activate J-Alert to warn residents of missile strikes or invasions. Officials would issue evacuation orders and safety instructions while police, fire services, and rescue teams responded as needed
What Regional Risks Could Lead to a Crisis?
Several geopolitical risks could escalate into a military emergency, including:
- China’s maritime disputes over the Senkaku Islands and the East China Sea
- North Korea’s missile threats
- Territorial disputes with Russia
- The impact of disputes between China and Taiwan on Okinawa and Japan’s southwestern islands
Evacuations and Multilingual Challenges
In case of an imminent attack, Japan has designated evacuation shelters (避難所, hinanjo) for emergencies, including natural disasters and military threats. These are typically located in schools, community centers, and gymnasiums and are managed by local governments. While some provide multilingual support, most operate primarily in Japanese, which could pose challenges for foreign residents.
Local authorities may or may not provide interpreters for non-Japanese speakers. Multilingual support might exist in major cities, but access to interpretation services would be limited in smaller municipalities. Foreign residents should prepare by downloading translation apps or carrying a printed emergency phrase guide in Japanese.
A military emergency could close airports and seaports. If travel routes were blocked, foreign residents would need to seek guidance from their embassies, which might arrange emergency repatriation flights or alternative evacuation methods.
The U.S. Military
In a military emergency, the Japan-U.S. Security Treaty (日米安全保障条約, Nichibei Anzen Hoshō Joyaku) would likely come into effect, meaning U.S. military actions would be expected to assist in Japan’s defense. There are 120 U.S. military installations in Japan, with around 32 located in Okinawa. Major bases include Yokota Air Base in Tokyo, Yokosuka Naval Base in Kanagawa and Kadena Air Base in Okinawa. Okinawa has many U.S. military installations, making it a key strategic location for U.S. forces in the region.
Under the Japan-U.S. Security Treaty, the U.S. military is obligated to assist in Japan’s defense in the event of an armed attack on Japanese territories. Both nations regularly conduct joint exercises to enhance interoperability and deterrence, ensuring preparedness for such scenarios.
However, the extent and speed of U.S. involvement would vary depending on the severity of the situation and U.S. politics. While the U.S. has a strong commitment to Japan’s defense, its response might not be immediate or purely military. Diplomatic measures, such as sanctions, could also play a role.
Moreover, the nature of the attack matters:
- If Japan is attacked by a nation-state (e.g., China or North Korea), U.S. involvement would likely be more direct due to alliance obligations and global security interests.
- If the attack is a limited skirmish, cyberattack or gray-zone conflict, the U.S. might first respond with non-military actions, such as diplomatic efforts, economic sanctions or cyber defense assistance.
- The U.S. response may also depend on Japan’s request—Japan must invoke the treaty for U.S. involvement.
The International Response
The likely scenario is less exciting than the movies. The Government of Japan would probably declare a national emergency and immediately shift to defense measures. At the same time, it would condemn the attack internationally, push for sanctions and intervention through the United Nations Security Council, and strengthen ties with allies.
When North Korea fired a missile over Japan in 2022, the government activated J-Alert. It also briefly halted trains and advised residents in northern Japan to take cover. Officials condemned the launch, called for a U.N. Security Council meeting, and later held routine military drills with the U.S. and South Korea. Most people quickly went about their day after a short scare.
However, if attacks continued, Japan’s Self-Defense Forces (JSDF) would take countermeasures under self-defense principles. Under the Japan-U.S. Security Treaty, the U.S. military would assist in Japan’s defense. This includes possibly conducting airstrikes, naval blockades or other military actions against the attacking nation.
What Happens to Visas and Residency Status?
There’s no direct precedent for how Japan would handle visas and residency during a war. But if a prolonged conflict or national emergency were to break out, you can bet that things would get chaotic. Immigration services might be delayed, suspended or even shut down entirely in affected areas.
During World War II, Japan heavily restricted immigration, travel and foreign entry, both for security reasons and wartime control. Only Axis-aligned foreigners (e.g., Germans, Italians and some neutral diplomats) were allowed limited access to Japan.
After the war, Japan (under Allied occupation) restricted foreign entry, except for diplomats and those with special permits. This gradually changed after the 1951 Treaty of Peace with Japan, allowing foreign nationals to return. By the mid-1950s, as Japan’s economy recovered, investment, corporate activity and foreign residency resumed. This marked a new phase of international engagement.
The 2011 Tohoku Earthquake Gives an Idea of The Response
However, those restrictions were Allied policies. For a modern example, we can look at past crises—like the 2011 Tohoku Earthquake and Fukushima disaster—to get an idea of what Japan might do. At that time, the government loosened immigration rules to accommodate foreigners stuck in Japan.
- Automatic Visa Extensions: The government automatically extended visas for those unable to renew them when services were disrupted.
- No Overstay Penalties: Authorities did not penalize foreigners who overstayed due to flight cancellations and border disruptions.
- Eased Departure Rules: Officials allowed foreign residents to leave quickly by relaxing exit procedures.
- Embassy-Coordinated Evacuations: Several governments arranged chartered flights and ships to evacuate their citizens.
- Temporary Protection Visas: Authorities granted special residency permits to foreign nationals who couldn’t safely return home.
Restrictions Could Be Like COVID-19 Lockdowns
During COVID-19, Japan imposed some of its strictest immigration restrictions in modern history, including:
- Border Closures: Japan completely banned tourists and denied re-entry to many long-term foreign residents who left the country.
- Strict Entry Requirements: Only Japanese citizens, diplomats, and select essential workers could enter. Over time, authorities granted certain visa holders some exceptions.
- Mandatory Quarantine and Testing: Officials required travelers to take PCR tests, undergo government-monitored quarantine (3-14 days), and use tracking apps. They enforced hotel quarantine for arrivals from high-risk countries.
- Slow and Controlled Reopening: Authorities gradually allowed students, workers, and business travelers to return but imposed daily arrival caps.
Of course, war brings a whole different level of uncertainty compared to a natural disaster. Depending on the situation, Japan could also impose travel restrictions, airport closures, or border shutdowns. If you’re a foreign resident, your best bet would be to keep an eye on your embassy’s updates. Have an exit plan and be ready to move fast if things start escalating.
While Japan has maintained peace for nearly 80 years, rising regional tensions make it important to understand what could happen in a military emergency. Is Japan prepared for an international crisis? Share your thoughts in the comments below.
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