In January, during a lengthy New York Times interview with President Donald Trump, one of the paper’s reporters asked him whether he saw “any checks” to his “power on the world stage.” Yes, he answered: “There is one thing. My own morality. My own mind. It’s the only thing that can stop me, and that’s very good.” Another reporter asked about international law. “I don’t need international law,” he explained. “I’m not looking to hurt people. I’m not looking to kill people.”
That attitude—save the last two sentences—has been on dramatic display in recent months. Already it has served as the basis for the extrajudicial execution of more than 150 people claimed to have been transporting drugs on the high seas and the deaths of at least a hundred people during the illegal invasion of Venezuela to arrest President Nicolás Maduro, provoke regime change, and gain access to that country’s oil.
But never has Trump’s willful blindness to legal limits been more evident than in his decision to start a war with Iran. As of March 4 the death toll in Iran from the joint US–Israeli military assault, underway since Saturday, had risen to nearly eight hundred. That number includes the country’s supreme leader, Ayatollah Ali Khamenei, and many of its top officials, but also reportedly at least 175 people at a girls school—many of them children between the ages of seven and twelve—that was in session when bombs struck.
Trump’s war with Iran may not trouble his “morality,” but it is manifestly illegal. It violates what is often described as the first principle of international law, enshrined in the United Nations Charter, which prohibits nations from using or threatening to use force against another nation except in self-defense or when authorized by the UN Security Council. Neither condition obtains here. Early Saturday morning, Trump issued an eight-minute video in which he claimed that he had acted to defend the American people from “imminent threats.” To justify that claim he cited historical Iranian wrongdoing dating back to the 1979 hostage crisis, as well as its support of terrorist groups, but he identified no actual imminent threat. He repeatedly said that Iran could never be allowed to have a nuclear weapon, but he also stated that a June 2025 air attack on Iran’s nuclear facilities had already “obliterated” its nuclear capability. And he urged the Iranian people to “take over your government,” an explicit endorsement of regime change having little to do with self-defense. (As no one disputes, Khamenei was a truly despotic leader, responsible for inflicting terror and death on his own people and on those of many other countries. But there are many despots around the world, and no principle of international law makes Donald Trump the arbiter of which ones stay in power and which ones should be killed.)
In a letter submitted to Congress two days later, the president omitted his previous, unsupported claim of an imminent threat. Instead he vaguely asserted that he had acted in defense of Americans at home and abroad, as well as “in collective self-defense of our regional allies, including Israel.” But in the absence of any ongoing attack, or any evidence that Iran was planning an imminent attack, neither the United States nor Israel had any authority to start a war against another sovereign country.
Trump’s unilateral action also violated the Constitution, which gives Congress, not the president, the power to declare war and authorize more limited military actions (referred to in the Constitution as “letters of marque and reprisal”). That allocation of responsibility was deliberate. As George Mason explained at the time, the aim was for “clogging rather than facilitating war.” The framers worried, justifiably, that presidents would be tempted to use military force, and they wanted to ensure that the young, vulnerable nation did not enmesh itself in military conflict unless the most representative branch of government first authorized doing so. Here, as under international law, there is a narrow exception allowing the president to repel invasions or imminent attacks, since these may not leave time to get approval from Congress. But Trump has pointed to no such conditions here.
The Harvard Law professor Jack Goldsmith has argued that law is irrelevant when it comes to war-making, and as a matter of realpolitik he is probably right, at least for powerful nations like the US. There is no effective mechanism to hold the president accountable for running roughshod over the Constitution or the UN Charter. Courts are historically reluctant to get involved, and the Security Council, of which the US is a permanent member, can only act unanimously.
But in another sense the legal questions are not just relevant but essential. A world in which only a leader’s subjective “morality” constrains any nation from launching aggressive military attacks against other nations is not only a world governed by men rather than by law but also one in which power rules absolutely. If Trump can depose any leader he likes, what is to stop Russia or China acting similarly against their foes? (Russia, of course, already has tried, in its war on Ukraine.) Is that the world we want to live in?
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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.
When accordion-like notions of prevention are coupled with advances in modern technology, the risks of illegal war-making multiply dramatically. President Barack Obama campaigned on ending the war in Iraq and announced the conclusion of a lengthy troop withdrawal in 2011. But he neither abandoned the concept of preventive war nor sought to hold Bush administration officials accountable for the crimes they committed in its name. One of Obama’s most enduring legacies is the use of remote assassinations by drone strikes. By the time he left office he had authorized a reported 542 drone strikes to execute people security agencies had placed on “kill lists” based on secret allegations that they were terrorists. Those strikes ultimately killed an estimated 3,797 people. Because placement on the kill list required no trial or conviction, everyone the drone program killed was at least presumptively innocent. Many of the victims, moreover, were not even on the list at all; they just happened to be in the wrong place at the wrong time when a drone strike fell.
Obama claimed that this tactic was justified to stop terrorists from taking action against the US in the future. But the strikes were not in response to any actual or imminent attacks on US persons or interests. They rested on the unknowable prediction that the people they targeted would harm us at some point in the future. There is, unfortunately, a direct line between Obama’s kill list and Trump’s illegal executions of drug smugglers. In both instances the president claims, without any public trial or even accounting, that a person poses a future threat to the United States, and tells someone to push a button that will end that person’s life (as well as those of the people around him). Obama’s supporters might say there is a difference between targeting alleged terrorists associated with a group that had attacked us and targeting suspected drug runners, and they would have a point. But the legal and conceptual rationales—and the technological method—are the same.
The importance of adhering to legal constraints is only magnified by the technological advances that Obama exploited. It used to be that if the leader of one nation disapproved of the leader of another, he was unlikely to be able to dislodge him from power without committing substantial troops to the cause, with the likely result of a significant loss of life on his country’s side. The unpopularity of sacrificing one’s own people was probably a more effective constraint than international law.
Today, in contrast, war-making need not involve many troops on the ground. Sophisticated aerial missions, remote drone warfare, and cyberattacks have all radically reduced the human cost of military intervention, at least as long as one picks opponents that lack the wherewithal to respond in kind against one’s own people. No American soldiers died carrying out Obama’s drone strikes or Trump’s executions on the high seas. Thus far six US soldiers have been confirmed killed in the Iran war. As any economist could have predicted, as the human cost to one’s own side has fallen, the demand for such measures—at least by presidents—has risen.
Wars, needless to say, still impose substantial costs on the countries that start them, even setting aside the destruction and death they visit on the countries they target. The attacks on Venezuela and Iran will cost US taxpayers billions of dollars—billions that won’t be spent creating jobs, building houses, or providing health care, the things the American people actually want from their government. So although Trump believes that the only constraint on his war-making is his own “morality,” he may well learn that there is another factor: the American people. Wars tend to be popular when they begin and only lose support over time: think Iraq or Afghanistan. This war is already wildly unpopular; hardly anyone elected Trump to launch an attack on Iran. If the people find Trump’s morality an insufficient check on executive adventurism, they will have an opportunity to render judgment in the midterms. But November is a long way away, and meanwhile the administration’s latest adventure will keep squandering our taxpayer dollars and taking countless lives.
English (US) · 