As much as the world loathed Saddam Hussein, Saddam Hussein was the equalizing force in the Persian Gulf that kept Iran in check. When George Bush ordered the invasion of Iraq in 2003, he did for the Iranians what they were never able to do for themselves: He got rid of Saddam Hussein.

The level of distress within the military couldn’t be higher at this decision. I’ve even heard talk about some senior people in the military discussing resigning over this. The alternative to the withdrawal is to try to persuade the Iraqi government to let some troops stay, to make absolutely the maximum effort to have [that] insurance policy in the Middle East.

The Iranians are not going to attack Iraq with tanks and grenades. They don’t need to. They’ve already successfully shown that they can influence events there. The prize of the oil is in the Southern part of Iraq, and the Iranians are a steady influence there. The decision to withdraw was made in Baghdad, not by President Obama. The issues that we uncorked in 2003 — the Sunni/Shia, the Arab/Kurd, and in particular, the rise of Iran’s power in Iraq — were not stopped by 100,000 soldiers during the surge, and they haven’t been whittled back by 40,000 soldiers during the last two years. As the U.S. has stepped back from internal politics in Iraq, the Iranians have filled that void very comfortably, and will continue to do so.