World War II The
Axis powers in
World War II routinely invaded neutral countries on grounds of prevention and began the
invasion of Poland in 1939 by claiming the Poles had attacked a border outpost first. In 1940,
Germany invaded Denmark and Norway and argued that Britain might have used them as launching points for an attack or prevented supply of
strategic materials to Germany. In the summer of 1941,
Germany invaded the Soviet Union, inaugurating the bloody and brutal land war by claiming that a
Judeo-Bolshevik conspiracy threatened the Reich. In late 1941, the
Anglo-Soviet invasion of Iran was carried out to secure a supply corridor of petrol to the
Soviet Union.
Iranian Shah
Rezā Shāh appealed to US President
Franklin Roosevelt for help but was rebuffed on the grounds that "movements of conquest by Germany will continue and will extend beyond Europe to Asia, Africa, and even to the Americas, unless they are stopped by military force."
Pearl Harbor The
attack on Pearl Harbor by the
Empire of Japan on December 7, 1941 has been characterized as a preventive war. Many in the US and Japan believed war to be inevitable. Coupled to the crippling US economic embargo that was rapidly degrading the Japanese military capability, that led the Japanese leadership to believe it was better to have the war as soon as possible. In 1940, American policies and tension toward
Japanese military actions and
Japanese expansionism in the Far East increased. For example, in May 1940, the base of the US Pacific Fleet that was stationed on the
West Coast was forwarded to an "advanced" position at Pearl Harbor in
Honolulu,
Hawaii. The move was opposed by some
US Navy officials, including their commander, Admiral
James Otto Richardson, who was relieved by Roosevelt. Even so, the
Far East Fleet was not significantly reinforced. Another ineffective plan to reinforce the Pacific was a rather late relocation of fighter planes to bases located on the
Pacific islands like
Wake Island,
Guam, and the
Philippines. For a long time, Japanese leaders, especially leaders of the
Imperial Japanese Navy, had known that the large US military strength and production capacity posed a long-term threat to
Japan's imperialist desires, especially if hostilities broke out in the Pacific. War games on both sides had long reflected those expectations.
Iraq War The
2003 invasion of Iraq was framed primarily as a preemptive war by the
George W. Bush administration, although President
George W. Bush also argued it was supported by Security Council Resolutions: "Under
Resolutions 678 and
687—both still in effect—the United States and our allies are authorized to use force in ridding Iraq of weapons of mass destruction." At the time, the US public and its allies were led to believe that
Ba'athist Iraq might have restarted its nuclear weapons program or been "cheating" on its obligations to dispose of its large stockpile of
chemical weapons dating from the
Iran–Iraq War. Supporters of the war have argued it to be justified, as Iraq both harbored
Islamic terrorist groups sharing a common hatred of the United States and was suspected to be developing
weapons of mass destruction (WMD). Iraq's history of noncompliance of international security matters and its history of both developing and using such weapons were factors in the public perception of
Iraq's having weapons of mass destruction. In support of an attack on Iraq, US President
George W. Bush stated in an address to the
UN General Assembly on September 12, 2002 that the Iraqi "regime is a grave and gathering danger." However, despite extensive searches during the several years of occupation, the suspected weapons of mass destruction or weapons program infrastructure alleged by the Bush administration were not found to be functional or even known to most Iraqi leaders. Coalition forces instead found dispersed and sometimes-buried and partially dismantled stockpiles of abandoned and functionally expired chemical weapons. Some of the caches had been dangerously stored and were leaking, and many were then disposed of hastily and in secret, leading to secondary exposure from improper handling. Allegations of mismanagement and information suppression followed.
Twelve-Day War The
Twelve-Day War in June 2025 was a preventive war launched by
Israel to prevent
Iran from
developing nuclear weapons. While Israeli officials called the War a “preemptive strike,” the legal and strategic reality fit preventive rather than preemptive definitions. Preemptive strikes respond to imminent threats when the signs of attack are present, while preventive strikes respond to a generalized threats of war in more distant future and are based on calculations that fighting now is better than fighting later. Israel is removing the source of a threat by surprise and on their own timetable.
Iran War On February 28, 2026, the United States and Israel launched surprise attacks against Iran, triggering the
2026 Iran war. The strikes targeted several military and government sites and
assassinated several senior Iranian officials including Supreme Leader
Ali Khamenei. The United States and Israel framed the strikes as a preemptive war of
self-defense. The
Trump administration presented various
rationales for the war, including warding off an imminent Iranian threat, pre-empting Iranian retaliation against U.S. bases and assets after an expected Israeli attack on Iran, to prevent Iran from obtaining a
nuclear weapon, and to
achieve regime change by bringing the
Iranian opposition to power. U.S. President
Donald Trump said that the strikes aimed to "prevent this very wicked, radical dictatorship from threatening America and our core national security interests." == Case for preventive nuclear war ==