Amid US President Donald Trump’s call for allies to send warships to escort oil tankers through the Strait of Hormuz, one question has emerged — How far can pacifist Japan go to support its closest ally
in a conflict? The legal options available to Prime Minister Sanae Takaichi and the past precedents, News18 explains.
JAPAN’S STAND ON INTERNATIONAL DISPUTES
After its defeat in World War Two, Japanhad adopted a US-drafted constitution that renounced the use of force to settle international disputes, CNN and other media reports stated. It has significantly shifted toward a more “proactive” defence posture in recent years. Within those limits, Takaichi can deploy Maritime Self-Defense Force vessels on law-enforcement operations overseas.
Article 9: Enacted in 1947, this clause states that Japan “forever renounce[s] war as a sovereign right of the nation” and prohibits the maintenance of “land, sea, and air forces, as well as other war potential”.
Self-Defence Forces (SDF): Despite Article 9, Japan established the JSDF in 1954. Legally, these are not considered a “military” but a force for “minimum necessary” self-defence.
An example was the anti-piracy mission off Somalia and in the Gulf of Aden, which Japan joined in 2009, after revising legislation to allow Japanesewarships to protect vessels of all nationalities.
JAPAN’S POLICY SHIFTS FROM 2022 TO 2026
The Japanese government has moved toward what it calls “proactive pacifism” to address regional threats from China, North Korea, and Russia.
In December 2022, Japan announced its largest military buildup since WWII, aiming to increase defense spending to 2% of GDP by 2027.
Japanhas authorised the acquisition of long-range missiles capable of striking enemy bases if an attack is imminent.
A 2014 reinterpretation (and 2015 law) allows the SDF to assist an ally under attack, even if Japan itself is not directly targeted, provided certain strict conditions are met.
Japan has recently relaxed long-standing bans on exporting lethal weapons, including next-generation fighter jets being co-developed with Italy and the UK.
The administration of Prime Minister Sanae Takaichi has taken a more hawkish stance, openly considering military responses in a “Taiwan contingency” and pushing for a formal amendment to Article 9 to clarify the SDF’s status.
HOW JAPAN RESPONDED TO TRUMP’S REQUEST
After Trump’s request, Defence Minister Shinjiro Koizumi told the Japanese parliament on Monday that a similar policing action could be considered “if further measures by the SDF are deemed necessary”.
But that framework is designed for policing, not combat. Applying it to operations where Japanese forces could confront a state actor such as Iran would be legally problematic, said the CNN report.
WHAT THE LAW SAYS
Japanhad passed security laws in 2015, allowing it to use force overseas in limited circumstances. That is permitted only if an attack, including on a close security partner, threatens Japan’ssurvival and no other means are available to address it, said the CNN report.
The laws permit a broader use of force than possible in anti-piracy operations, but the legal threshold for invoking them is far higher. Takaichi would need to argue that the disruption to energy supplies caused by the closure of the Strait of Hormuz constituted an existential threat, a case likely to face stiff political and public opposition.
The legislation has never been used and Takaichi this week said Japan would prioritise diplomatic efforts to de-escalate tensions in the Middle East.
HOW HAS JAPAN RESPONDED IN THE PAST
1991 Gulf War: Japan contributed money rather than personnel, a decision criticised by the US and other nations as ‘chequebook diplomacy’. After hostilities ended, it dispatched minesweepers to the Persian Gulf, marking the SDF’s first ever overseas deployment.
September 11, 2001: Japan sent MSDF vessels to the Indian Ocean to refuel and support US-led operations in Afghanistan. That mission ran for eight years but did not involve combat or escort missions.
Iraq, 2004: Japansent about 600 ground troops to Iraq for reconstruction work, along with aircraft to help transport supplies and personnel. The soldiers were only allowed to use force as a last resort, and were guarded by Dutch and Australian troops during their two-year stint.
2019: After attacks on tankers that Washington blamed on Iran, Japandiverted a destroyer and patrol plane from anti-piracy operations near Somalia to gather intelligence in the Gulf of Oman, the Arabian Sea and Gulf of Aden. However, they stayed outside the Strait of Hormuz and the Persian Gulf.
IS US ACTION IN LINE WITH INTERNATIONAL LAW?
Under the United Nations Charter, the use of force is generally prohibited unless authorised by the UN Security Council or justified as self-defence against an armed attack.
For a country that has long been a staunch supporter of international law, that uncertainty could further limit how far Tokyo is willing to go.
Legal experts are divided over whether the US strikes on Iran meet that threshold and Takaichi has so far declined to say what Japan’s position is.
KEY FAQS
What is Japan’s current role in the Strait of Hormuz conflict?
Japan depends on the Middle East for over 90% of its crude oil imports, most of which must pass through this narrow chokepoint. Japan has declined to send warships to the region. Prime Minister Sanae Takaichi stated that Japan’s war-renouncing Constitution strictly limits overseas military deployments, making such a mission legally complex. Japanese shipping companies, including NYK Line, have halted transit through the strait due to safety risks.
Has the US requested Japan’s military assistance?
On March 14, 2026, President Trump publicly urged Japan, South Korea, China, and NATO allies to send ships to help unblock the strait. As of March 18, Trump abruptly withdrew his request, stating the U.S. no longer “needs” or desires assistance from Japan, Australia, or NATO countries due to “military success”.
Who is currently blocking the Strait of Hormuz?
Roughly 20% of the world’s oil and liquefied natural gas (LNG) passes through the strait daily.
Iran has effectively closed the strait to vessels from the U.S., Israel, and their “Western allies” in retaliation for attacks that began on February 28, 2026. Iran claims the waterway remains open to “non-enemy” nations, but multiple commercial ships have been hit by projectiles. The closure has contributed to global oil prices soaring above $100 per barrel.
With CNN, agency inputs
