Ultimate responsibility for the Iran war lies with Trump, but the road to it was paved by his predecessors—of both parties. After the terrorist attacks of September 11 George W. Bush declared an amorphous, global, and preventive “war on terror,” stretching the notion of preemptive war beyond any meaningful limits. A truly preemptive war responds to actual imminent hostilities. The notion of “preventive war,” by contrast, is not recognized in international law, and for good reason. It expands the concept of preemption to excuse interventions in the absence of an imminent threat; it is far more speculative, and therefore far more dangerous.
Under that theory Bush claimed the right to attack any international terrorist organization anywhere in the world, effectively declaring a global war. The administration’s “preventive” measures included disappearing suspects into secret CIA “black sites” where they were tortured, including by waterboarding. It also detained more than seven hundred Arab Muslims in the United States using pretextual immigration charges and only then investigated them to determine whether they had terrorist ties. Not one was charged with any terrorism-related crime.
Bush’s embrace of preventive military action also led him to launch a disastrous war against Iraq, which had neither attacked us nor credibly threatened to do so. Bush claimed that Iraq’s president, Saddam Hussein, was a despot, which was certainly true—but no more justification for an invasion than Trump’s similar charge against Khamenei. He also claimed that Iraq had weapons of mass destruction, which was not true—and at any rate no justification for war absent a credible threat that Iraq intended to use them to attack the United States imminently.
Trump’s administration is deploying a similarly expansive conception of prevention. Secretary of State Marco Rubio claimed a kind of second-order preemption as justification for starting a war with Iran. He said that Israel was likely to attack Iran even without us, and that after that attack (which would itself have been illegal), there was a risk that Iran would respond by attacking US targets. But as the Tel Aviv University law professor Eliav Lieblich has explained, that defense fails on multiple grounds. It is doubly speculative, as it depends on predicting the future actions both of Israel and Iran. It presumes, falsely, that the US had no leverage over Israel’s decision, despite Israel’s deep dependence on US support. And in any case its factual premise was contradicted by Trump himself, who denied that Israel dragged us into the war. This sort of reasoning is precisely why expansive concepts of preventive war cannot be squared with international law.