Over the past two years, Syria's descent into civil war has provoked alarm and horror in Washington. While officials have argued over the extent to which the United States can and should intervene, everyone agrees that the conflict poses a humanitarian catastrophe and a threat to U.S. interests across the Middle East, including to the stability of allies, the struggle against Islamist extremism and the effort to keep weapons of mass destruction out of terrorist hands.
Lately, however, another argument has crept into the debate: the idea that, while unquestionably tragic, Syria's slow-motion unraveling might not be an unmitigated calamity for the United States. Rather, it could carry a Machiavellian upside by embroiling Iran, our foremost enemy in the region, in a costly, protracted struggle with al-Qaida. Syria, the theory holds, could be for Iran what the Iraq war was for the United States.
For the Obama administration, under fire for its handling of the crisis, this could be an appealing notion - and a convenient rationalization for not attempting more decisive intervention that might stop the spiral of violence.
But there's good reason - beyond its ugly moral calculus - that this argument is mostly whispered on the margins. Under scrutiny, it withers.
For starters, the argument presumes that the Syrian conflict is bogging down the Iranians, sapping their strength and distracting them from more vital interests. Unfortunately, the evidence suggests that as Tehran has been riding to the rescue of Syrian President Bashar Assad, it has made disturbing inroads elsewhere, including Yemen and Iraq.
That's because the instability the Syrian conflict is fueling across the Middle East is largely good for Iran: Sectarian polarization is driving anxious Shiite populations closer to Tehran, while refugee flows are weakening key U.S. allies such as Jordan and Turkey.
Iran, meanwhile, is suffering no meaningful blow-back for its deadly interference in Syria. On the contrary, protracted bloodshed there fosters regional conditions in which Iranian power is likely to thrive.
Involvement in Syria also hasn't done - and won't do - anything to set back Iran's strategic trump card: its nuclear program. In the two years since the uprising against Assad began, Tehran has made steady progress toward weapons capability. It has expanded its stockpile of enriched uranium, installed next-generation centrifuges and moved forward with a heavy-water reactor that will provide an alternative path to a bomb.
Nor does Iran's aid to Assad seem likely to exhaust the Islamic Republic. Although surely an unwelcome burden at a time when the regime is battling economic sanctions, Tehran's approach to the conflict has not been an Iraq-style commitment of hundreds of thousands of ground troops. Rather, it's pursuing a "light footprint" more akin to the Obama administration's preferred approach to the war against terrorism by relying on a small number of its version of special-operations forces, the Quds Force, who are bolstering local proxies.
Of course, there is another aspect of the Iraq war the Obama administration might consider before wishing a similar experience on Iran: namely that, in the end, the United States prevailed.
When President Obama took office in 2009, the back of the al-Qaida-linked insurgency had been broken, Iranian-affiliated militias in southern Iraq had been routed, and the framework was in place for a long-term partnership between Washington and Baghdad.
What might an analogous outcome for Syria look like? We've had a preview of that future over the past month, as a surge of support from Iran and Hezbollah enabled Assad to make significant battlefield gains against the rebels.
The Iraq war was devastating for the United States largely because, until the 2007 surge, we were losing. No one in the Middle East watching the recent developments in Syria would say that of Iran.
The Obama administration has reportedly decided to send light weapons and ammunition to the opposition. But even if this starts to reverse the momentum of Assad and the Iranians - an optimistic assumption - a return to a bloody stalemate is still a win for Tehran.
That's because Assad doesn't need to reconquer all of Syria for the Iranians to emerge successful. Every day that Assad stays in power thanks to Iranian help, Tehran shows that it can prevent the Obama administration from achieving its stated goal - Assad's ouster - and that Iran, not the United States, is the relevant power in the region.
And the longer the fighting drags on, the more radicalized Syrian society becomes and the deeper the Iranians can entrench themselves.
This suggests a final flaw in likening the U.S. experience in Iraq to Iran's intervention in Syria. After turning the corner in Iraq, the United States under the Obama administration walked away. You can bet that in Syria, Iran's leaders won't make the same mistake.
Vance Serchuk is a Council on Foreign Relations-Hitachi international affairs fellow based in Tokyo at the Canon Institute for Global Studies.