Prominent (neo)conservatives who promoted the war, such as Sen. John McCain (R‑Ariz.) and Washington Post blogger Jennifer Rubin, have blamed the U.S. military drawdown from Iraq for a rise in Iranian influence. That popular contention willfully ignores that Iran became a beneficiary of the war as a result of Saddam Hussein’s removal, not that of American troops.

Before the 2003 invasion, Iraq war proponents were so focused on removing Saddam from power that they largely overlooked how it would enable Tehran to back its political allies in Baghdad with far greater impunity. Take Iraq’s current Prime Minister, Nouri al Maliki, head of the Shiite (Dawa) political party. From 1982 until the U.S.-led invasion, Maliki found refuge in Iran while other Dawa members found refuge in Syria. Why Iran and Syria? According to Dawa, “These two countries were most sympathetic to the cause against Saddam’s regime at the time.”

That was also when top officials in Washington were assisting Baghdad’s secular Ba’athist regime in its ongoing conflict against Iran and refused to punish Saddam for gassing Iraqi Kurds. The Iran-Iraq War (1980–88) ultimately devolved into a protracted stalemate, allowing the rivals to weaken each other. Because the region remained divided, neither side could achieve hegemony and shut out American influence. As Henry Kissinger reportedly quipped, “It’s a pity they both can’t lose.”

In August 1988, after the bloody Iran-Iraq War finally ended with a U.N.-mandated ceasefire, Saddam did not intend to preserve the status quo: His forces invaded Kuwait in August 1990. The immediate objective of the resulting U.S.-led international coalition was to expel Iraqi forces from Kuwait, and to avoid what President George H.W. Bush’s Secretary of State James Baker warned, “something that would result in the fragmentation of Iraq because we didn’t think that would be in our national interests.”

Washington’s larger aim was to prevent Iraq from dominating the Persian Gulf. For the next 12 years, no-fly zones and a sanctions regime contained Saddam’s expansionist tendencies. Iran’s strength grew, Iraq’s strength receded, and the balance of power in the Gulf remained reasonably intact. That all changed dramatically after March 2003. 

Bush administration officials, and their Democratic and Republican supporters on Capitol Hill, underappreciated the wider geopolitical ramifications of dethroning Iran’s principal regional counterweight. Realist scholars pointed out at the time that no amount of prewar planning or “boots on the ground” could have prevented the Islamic Republic’s push into a neighboring country with a 60 percent Shiite majority. By 2010, leaders in Tehran helped create Prime Minister Maliki’s Shiite-led government, and according to reports, began “calling in favors among its allied factions in Iraq.”

It is useful to keep in mind that many prominent politicians and pundits who originally promoted the war have now seized on expanded Iranian power to press for action against its regime. These proponents of perpetual aggression convincingly illustrate what Austrian economist Ludwig von Mises described as the deception of government intervention: When the government perceives a problem, it intervenes to solve it, but instead of solving the initial problem, the intervention creates two or three further problems.

Those who blame America’s troop withdrawal for increased Iranian influence have their causation wrong. The preventive war of choice they were so confident would yield a positive outcome helped strengthen Iran’s geopolitical assertiveness and limit U.S. policy options across the region.