Can we afford Iran?

A Patriot missile is launched as part of the Patriot Air Defense System at White Sands Missile Range in New Mexico. | Corbis via Getty Images This story appeared in Today, Explained, a daily newsletter that helps you understand the most compelling news and stories of the day. Subscribe here. President Donald Trump’s on-again, off-again war with Iran is officially on again. (So recursive is this never-ending conflict, in fact, that I had to search my inbox to confirm I hadn’t already written…