Most Iraq watchers believe Maliki wants to ask for U.S. troops. But the problems — in addition to the chronic Iraqi practice of putting off hard decisions until the last minute — are formidable. Perhaps the most serious is Maliki’s political dependence on the Shiite party of Moqtada al-Sadr, an Iranian client. Sadr is threatening armed resistance if U.S. troops stay, and the offensive already underway by Iranian-sponsored militias shows that Tehran is ready to fight.

Administration officials nevertheless argue that the danger of Iranian hegemony in Iraq — and hence the importance of a stay-on force — is overstated by analysts such as Kagan. “Iran is struggling with its own economy,” Antony Blinken, a senior aide to Biden, told me. “Infighting among Iranian leaders has undercut its ability to make decisions about domestic and foreign policy,” and the uprising against the Syrian regime has further shaken Tehran’s confidence.

Maliki, Blinken says, has proven himself a nationalist who will resist Tehran’s diktats, and Iraqis will not tolerate a Persian puppet.