1. Iraq is 168,754 mi² and Iran is 636,400 mi²; that is, Iran is geographically 3.77 times bigger than Iraq, almost 4 times as big.

2. Iraq’s population when invaded was 26 million. Iran’s population today is 81 million.

3. General Eric Shinseki testified before Congress prior to Bush’s invasion that based on the US military’s experience in the Balkans, 800,000 troops would be needed to provide security to Iraq. Secretary of Defense Donald Rumsfeld insisted on 100,000 troops, wrongly believing he could pull them out in 6 months. Bush’s viceroy in Iraq, Paul Bremer, later admitted that “we never had enough troops” in Iraq. 

4. Since Iran is 3 times as populous as Iraq, by Shinseki’s correct calculation, the US would need 2.4 million troops to occupy Iran.

5. The US total military personnel count is about 2,141,900, of whom 1, 281,900 are active duty and the rest reservists.