After months of escalating tensions, the United States and Iran came closer to outright war in the last week than any other time in the past four decades. In a series of tweets on Friday, President Donald Trump claimed that he had authorized strikes on Iran in response to Tehran’s downing of a drone, only to back off after he learned that the attack would result in around 150 Iranian deaths. For weeks, National Security Adviser John Bolton, Secretary of State Mike Pompeo, and CIA Director Gina Haspel have urged military action amid a series of provocations by the Iranian regime; Trump opted instead to reach out through Oman and offer a diplomatic solution to Tehran.
It was the right call: A military engagement with Iran would be a complete mess. But in pushing for armed conflict, Trump’s coterie of advisors have revealed the extent of their hubris — and underscored U.S. military’s greatest vulnerability of the 21st century.
In going to war with Tehran, the U.S. would face a military force that outstrips anything it’s faced since the Vietnam War. A 2018 analysis from the Center for Strategic and International Studies (CSIS) suggests that Iran likely has 523,000 active-duty military personnel and 250,000 reserves ready to meet any invading force — far more, as The Washington Post notes, than the 450,000 Iraqi personnel who faced off against U.S. forces during the 2003 invasion. Despite the fact that, as CSIS notes, Iran’s weapons systems are “obsolete, obsolescent, or of relatively low quality,” a conflict would certainly require more than the 120,000 U.S. troops then-acting Defense Secretary Patrick Shanahan suggested deploying to the region in May. After all, the U.S. wouldn’t just need to neutralize Iranian military assets and force a political surrender: The Pentagon would have to pacify a population three times larger than Iraq’s, spread across three times as much land — a major investment of resources and personnel that would weaken its ability to adapt to “great power competition” from Russia and China elsewhere in the world. Invading a country is one thing; occupying it is another.