29 U.S. conventional military capabilities, especially combined with those of its likely allies, are of course far superior to those of Iran. In many recent years the size of the U.S. defense supplemental alone exceeded the entire Iranian defense budget. But a fight with Iran would not be a fair or clean fight. Winning in any meaningful sense might prove costly. Escalation If Iran’s advantage lies in broadening and widening a conflict once begun, how might we expect its leaders to go about it? At least three types of escalation are open to Tehran: horizontal, vertical and domain. Horizontal escalation involves the spread of hostilities from beyond the immediate area of conflict to additional geographic areas and political actors.13 Iran’s means and methods, as discussed above, give it the ability to escalate horizontally within the Middle East region and beyond to include Europe and the United States. Vertical escalation involves the employment of new or increasingly potent weapons systems, attacking new types of targets, or introducing additional types of forces into the conflict.14 What begins as essentially a fight between U.S. and allied air and naval strike assets and Iranian air defense assets could be quickly expanded by Iran to the use of offensive missile systems and naval surface and sub-surface forces in retaliation. Iranian escalation to the employment of WMD (if a war occurred after an Iranian breakout) seems unlikely short of an imminent threat to the regime, but that threat would be hanging in the air as fighting escalated. Domain escalation refers to the expansion of the conflict from the purely military domain to the diplomatic, economic and social domains, in which Iran has some advantages. In summary, an attack on Iran could produce dynamics that would push either or both sides to escalate the conflict even if neither had an HOUSE_OVERSIGHT_018113