Although President Trump apparently called off a planned airstrike on Iran at the last minute in late June, he subsequently warned Iranian leaders that the military option was still very much on the table. He emphasized that if the United States used force against Iran, Washington would not put boots on the ground but would wage the conflict entirely with America’s vast air power. Trump exhibited no doubt about the outcome, asserting that such a war “wouldn’t last very long,” and that it would mean the “obliteration” of Iran.

His boast was eerily reminiscent of the statement that Kenneth Adelman, a former assistant to Secretary of Defense Donald Rumsfeld and a prominent figure in the U.S. foreign policy community, made prior to the Iraq War. Adelman famously predicted that a war to oust Iraqi leader Saddam Hussein would be a “cakewalk.”

The notion that a looming war will produce a quick, definitive victory for the “right” side is a fantasy that has lured numerous statesman throughout history. Occasionally, the prediction even turns out to be true, as it did for the United States in the 1898 Spanish American War and the 1991 Persian Gulf War. Far more often, though, a predicted “cakewalk” turns into a multi-year human meat grinder, as in the U.S. Civil War and World War I. Even if subsequent events do not produce a bloodbath on such a monstrous scale, the war frequently becomes a prolonged, futile, and counterproductive mission. Washington’s military interventions in Vietnam, Iraq, and Afghanistan fall into that category.

Trump’s rosy assurance that a war against Iran would be easy, quick, and decisive is especially misplaced. As I outline in a National Interest Online article, Tehran has multiple ways to retaliate for a U.S. attack, including using its Shia religious allies in Lebanon, Iraq, Yemen, and Bahrain to damage U.S. military and commercial targets, as well as inflict casualties on U.S. military personnel. Even pinprick attacks can cause a distressing toll over time, and Iran is more than capable of mounting such a campaign.

Unfortunately, President Trump is hardly the only one who embraces the delusion that a war against Iran would be the proverbial cakewalk. Ultra-hawkish Sen. Tom Cotton (R‑AR), a rising conservative star in the Republican Party, quipped that the conflict would be over in two strikes, “the first strike and the last strike.”

That is a frighteningly cavalier attitude. It’s worthwhile recalling how Adelman’s prediction of a cakewalk war in Iraq turned out. At last count, the United States has spent well over a trillion dollars trying to pacify and stabilize Iraq. Worse, more than 4,400 American soldiers have perished in that effort, with thousands more suffering wounds—many of them severely life-altering.

A war against Iran likely would be much worse. Iran is a larger country, both in terms of area and population. Although the Iranian military has been weakened over the years as a result of U.S.-led international economic sanctions, it still is substantially more capable than Saddam Hussein’s decrepit army and the ragtag insurgent militias the United States later confronted in Iraq. Rep. Tulsi Gabbard (D‑HI), a military veteran and an outspoken candidate for the Democratic Party’s presidential nomination, likely is correct that a war in Iran would make the Iraq War look like a cakewalk. That outcome would be a bitterly ironic fulfillment of Adelman’s prediction about the earlier conflict. President Trump would be wise not to venture down such a perilous path.