In foreign policy, good ideas often emerge from bad decisions. Such was the case with the Powell Doctrine, a term typically associated with the American triumph over Iraq in the 1990–91 Gulf War. The doctrine did not, in fact, originate with its namesake, Colin Powell, who as chairman of the Joint Chiefs of Staff helped make sure the United States went into the war with a coherent military strategy. And the doctrine’s roots lay not in a success in Iraq, but in a disaster in Lebanon.

In 1982, after Israel invaded the civil war–torn country, a rift opened inside the Reagan administration. On one side were Secretary of State George Shultz and civilian officials on the National Security Council, who backed the idea of contributing U.S. troops to a multinational force that would stabilize Lebanon. On the other side were Defense Secretary Caspar Weinberger and the generals on the Joint Chiefs of Staff, who were far less enthusiastic, fearing that an ill-defined mission would drag the United States into an escalatory spiral not unlike the one that had proved calamitous in Vietnam. The hawks won the debate, casting dovish concerns as reflecting a lack of faith in American military power that President Ronald Reagan had himself disparaged as “Vietnam syndrome.”

But it didn’t take long for Weinberger’s fears to be realized. Far from stabilizing Lebanon, the multinational forces soon became targets and combatants in the widening war. In October 1983, militants linked to Hezbollah used truck bombs to attack U.S. service members in a barracks at the Beirut airport, killing 241 of them. Inside the administration, the two camps once again split. This time, the doves prevailed. The United States refrained from hitting back against Hezbollah and its Iranian and Syrian sponsors, and in February 1984, Reagan withdrew American forces altogether.

Weinberger was determined to prevent a repeat of what he saw as an avoidable tragedy, especially as factions within the administration pushed for a more aggressive U.S. military response to Soviet-backed movements in Central America. He decided to give a major speech laying out his vision. For feedback on the draft, he turned to a young army major general who was serving as his principal military assistant: Powell, who later remarked that he had thought the Lebanon mission “never did serve a purpose” and was “goofy from the beginning.”

In his speech, delivered in November 1984, Weinberger declared that any plan to use military force should pass six tests. Vital national interests must be at stake. Washington must be willing to commit the resources it would take to achieve victory. Policymakers must have clearly defined political and military objectives. They must also be willing to continually reassess deployments and spending as conditions (and even their objectives) change. Policymakers must gain the support of the American people and Congress through candor and consultation. Finally, as Weinberger put it, “the commitment of U.S. forces to combat should be a last resort.” Reagan soon endorsed what became known as the Weinberger Doctrine, and later wrote in his memoir that its guidelines came to serve as a pillar of his administration’s foreign policy.

The doctrine faced its first real test in 1990, when Iraq invaded Kuwait and President George H. W. Bush had to decide whether to intervene militarily. By that time, Powell had risen to become chairman of the Joint Chiefs of Staff. Once Bush decided to use force, Powell set about making sure the plan passed Weinberger’s tests—and that it met two other conditions that Powell added to his former boss’s list: a clear exit strategy and international support. Ideally, the exit strategy would be victory: the adversary conceding the political objectives for which the war was being fought. And because chance shapes outcomes in war to a high degree, ensuring victory requires a wide margin for error. Translated into military terms, that meant using what Powell termed “decisive force.” Powell’s public briefings during the war and the military’s success catapulted him to prominence; the Weinberger Doctrine was now the Powell Doctrine.

Powell’s formulation was designed to restrain civilian leaders from resorting to military force simply to “do something.” He wanted to ensure that military force was rarely employed and that when it was, it was part of a strategy that integrated other elements of national power. This line of thinking had its critics. Some complained that the criteria unduly restricted American power. Others objected to a military officer’s setting criteria for civilian superiors. But Powell was adamant about his right to set such parameters. As he put it in an essay in these pages in 1992, “We owe it to the men and women who go in harm’s way to make sure . . . that their lives are not squandered for unclear purposes.”

In the years after the Gulf War, Powell took a dim view of the Clinton administration’s drift toward intervention in the Balkans. Needling the general at a 1993 meeting about whether to intervene in Bosnia, U.S. Ambassador to the UN Madeleine Albright grumbled, “What’s the point of having this superb military that you’re always talking about if we can’t use it?” Powell was aghast: “I thought I would have an aneurysm,” he later wrote. “American GIs were not toy soldiers to be moved around on some sort of global game board.” But when he himself later served as secretary of state during the George W. Bush administration, Powell played a consequential role in planning for and executing the wars in Afghanistan and Iraq, neither of which met his doctrine’s criteria. That he cautioned Bush about invading Iraq with a wry summary of the Powell Doctrine known as “the Pottery Barn rule”—you break it, you own it—does not exculpate Powell. In the end, he became a central player in the marginalization of his own ideas.

The Powell Doctrine remains the best way for U.S. presidents to decide why and how to go to war.

Yet even though the doctrine’s influence began to wane long ago, no administration ever truly repudiated it—at least until President Donald Trump’s second term. In late February, Trump launched a war on Iran without clearly delineated objectives, without consulting Congress or U.S. allies (other than Israel, Washington’s partner in the war), without obtaining an authorization for the use of military force, without exhausting diplomacy or economic coercion, and without an exit strategy.

The audacity of........

© Foreign Affairs