Michael Eisenstadt is the Kahn Fellow and director of The Washington Institute's Military and Security Studies Program.
Given recent frictions, the United States should take a number of steps to reduce the potential for escalation with Tehran and to avoid a broader conflict.
In recent weeks, U.S. forces have clashed in Syria with regime or Iran-supported pro-regime forces on at least a half-dozen occasions. This has raised concerns that with the impending military defeat of the Islamic State in Syria and the scramble to fill the resulting void, the United States may be on a collision course with Syria and its allies -- Iran, Hezbollah, and perhaps Russia. Escalating tensions elsewhere in the region between the United States, its allies, and Iran have compounded these concerns. So while the United States pursues informal "deconfliction" efforts with Russia, it needs to pursue parallel efforts to avoid a broader conflict with pro-regime forces and Iran.
Proliferating Friction Points
Recent U.S. military actions in Syria include a cruise missile strike on the al-Shayrat Air Base following a regime chemical attack on civilians (April 7); the aerial interdiction of Iran-supported pro-regime militias (May 18, June 6 and 8) and armed drones (June 8 and 20) that threatened Syrian rebels and coalition advisors near the border town of al-Tanf; and the downing of a Syrian Su-22 fighter that had attacked Syrian Democratic Forces units near al-Tabqa (June 18).
U.S. officials worry, moreover, that the liberation of Mosul might cause Tehran to conclude that it no longer benefits from the American presence in Iraq, and to encourage its Iraqi proxies to attack U.S. forces there.
Other potential flashpoints include the Persian Gulf, where Iranian warships frequently harass U.S. naval forces; the Golan Heights, where Iran and Hezbollah are creating an infrastructure to attack Israel (an Israeli drone strike there in January 2015 killed an Iranian general and several senior Hezbollah officials); Saudi Arabia and Bahrain, where Iranian claims of Saudi Arabian responsibility for the June 7 Islamic State (IS) attack in Tehran have raised concerns about possible Iranian subversion; and the Bab al-Mandab Strait, where Houthi rebels have attacked foreign warships using Iranian antiship cruise missiles and remotely controlled boat bombs.
The existence of so many friction points has raised fears that a clash (intentional, or accidental -- as when U.S. aircraft bombed Syrian troops in September 2016) might lead to a broader conflict with Iran. What does the past say about avoiding and managing escalation with Iran and its proxies?
Tehran's Risk Calculus
While pursuing anti-status quo policies that cause tension with other states, Iran is generally sensitive to risks and costs, and careful during crises and in dealings with more powerful adversaries such as the United States. It has generally emphasized reciprocity (responding in kind, at the level of the perceived transgression) as well as indirection, ambiguity, and patience (relying on proxies to provide standoff and a degree of deniability) in order to manage risk and limit the potential for escalation.
Thus, Tehran has repeatedly sought to avoid costly foreign adventures, even if it meant, in practice, abandoning beleaguered Shia communities -- as it did during the 1991 Shia uprising in Iraq, the 1998 slaughter of thousands of Shia Hazaras and eight Iranian officials by the Afghan Taliban, the 2006 war between Israel and Hezbollah, and the 2011 crackdown on Shia protestors in Bahrain. In each case, Iran responded indirectly via proxies, or after the fact -- sending the Iraqi Badr Brigades to aid the 1991 uprising in Iraq, arming the Afghan Northern Alliance against the Taliban, rebuilding Hezbollah after the 2006 war, and plotting to assassinate the Saudi ambassador in Washington DC in revenge for his country's role in quashing unrest in Bahrain.
In confronting foreign adversaries, Iran has done so directly when it could, and indirectly (through proxies) or by other means (such as terrorism or cyber) when it could not, or when logic dictated that it do otherwise. It has often tested adversary limits, backing off when faced with a firm response and reengaging under more favorable conditions later on. Thus, during the Iran-Iraq War (1980-88), Tehran countered U.S. naval convoys in the Gulf by indirect means (mines) and by attacking unescorted vessels, and when engaged decisively, fought as best it could. Iran was not deterred by U.S. intervention, but was forced to alter its approach and to eventually curtail its activities after a bruising series of encounters with the U.S. Navy.
During the U.S. occupation of Iraq, Iran armed Shiite special groups -- and assisted Sunni insurgents -- that targeted U.S. forces. It responded to a series of sticky bomb attacks on its nuclear scientists by attempting sticky bomb attacks on Israeli diplomats in Georgia, India, and Thailand in February 2012. Between 2011 and 2013, it countered cyberattacks on its nuclear program and economic sanctions with cyberattacks on the U.S. financial sector and Saudi Aramco. More recently, it responded to Saudi support for anti-regime rebels in Syria and other perceived provocations by intensifying its support for the Houthis in Yemen.
Tehran is also tactically flexible; when risks outweigh benefits, it will renege on threats -- though it may renew a challenge at a different place or time. Thus, when the United States returned an aircraft carrier to the Gulf in January 2012 after Tehran warned it against doing so, Iran failed to act, though it subsequently tried to shoot down an American UAV in the Persian Gulf that November and again in March 2013. And more recently, Iraqi proxies of Iran have not acted on past threats to attack U.S. combat forces if they returned to Iraq, as they needed American help to defeat IS.
Despite its general caution, Tehran is occasionally prone to high-risk behavior -- including the Marine barracks bombing in Beirut in 1983 (which it facilitated), the Khobar Towers bombing in Saudi Arabia in 1996, and the bungled plot to assassinate the Saudi ambassador in Washington in 2011. For this reason, interactions with Iran always entail a degree of unpredictability. And when it believes it has the upper hand (as currently seems to be the case, thanks to its successes in Syria), it is prone to press its advantage -- and perhaps to overreach.
The Syrian Cauldron
Iran's intervention in Syria is unprecedented; never before has it sent such large numbers of troops to support combat operations abroad. Yet its performance has been consistent with certain enduring principles: namely, it has avoided major risks, even when developments seemed to jeopardize its core interests. Thus, Iran never committed more than the minimum force needed to keep Syrian president Bashar al-Assad in power. It had some 700 men in Syria prior to its brief surge in late 2015 -- which raised force levels to about 3,000 -- most of whom it withdrew shortly thereafter, having experienced a spike in losses. The number is now believed to be about 1,500, a fraction of 1 percent of its ground forces. (By contrast, the United States deployed about one-third of its ground forces during its 2007-09 surge in Iraq.)
Iran has tried to cut its own losses in Syria by fighting to the last non-Iranian Shia proxy, even when its own forces would have been more effective. And when the tide of war turned against Assad in 2015, Tehran convinced Moscow to intervene, effectively enlisting Russia as a "Great Power proxy." Yet, if decisionmakers in Tehran have been strategically risk averse, Iranian personnel on the ground have been tactically risk acceptant. Iran has lost nearly 500 military personnel in more than five years of fighting in Syria -- though these losses pale in comparison to those of its proxy militias, which include, according to expert Ali Alfoneh, more than 1,900 Iraqis, nearly 1,100 Lebanese Hezbollah (1,700, according to Israeli estimates), nearly 700 Afghans, and nearly 150 Pakistanis.
Although pursuing an increasingly assertive regional policy, Tehran's handling of recent clashes in Syria reflects traditional Iranian caution. Thus, Iran relied on its Shia militia proxies to challenge rebel and coalition forces at al-Tanf. Once these forces were bloodied by U.S. airpower, Iran pulled them back and used armed drones to maintain pressure. They eventually opted to bypass the rebel- and coalition-held enclave. In pushing up against U.S. interests in Syria, Iran has gambled with expendable assets only. And the American tendency to respond proportionally, and somewhat predictably, has enabled Iran to test U.S. limits without incurring significant risk.
As long as Iranian forces operate in Syria and encourage their proxies to target rebel forces and their coalition advisors, a degree of friction and conflict will be inevitable. Yet for decades, the United States and Iran have avoided an open conflict, demonstrating that the potential for escalation may be overstated -- even as complacency is never warranted. To further reduce the potential for escalation, the United States should take a number of steps to influence Tehran -- as well as Damascus -- and avoid a broader conflict with either:
First, the United States should halt mixed messaging that could cause Syria or Iran to miscalculate. The Trump administration has intimated that it is not seeking Assad's departure and is not averse to military operations that enable the regime to regain control over much of Syria. Yet Washington has threatened military action should Damascus resume chemical attacks that enable such operations, and it has countered Iranian activities that, from Tehran's perspective, advance these twin goals. Such ambiguity encourages the type of testing that could lead to further clashes with the Assad regime and its Iranian backers.
Second, the United States should seek broad international support for its redlines in Syria. Iran, for its part, may be less likely to challenge U.S. interests if doing so might alienate key actors in Europe and Asia that Iranian president Hassan Rouhani has been courting. And Washington should continue to engage Moscow as part of its efforts to "deconflict" operations and influence Syria and Iran in order to avoid a broader conflict with Russia and its partners.
Third, redlines must be continually tended to, so that U.S. focus and commitment are not questioned. When tested by Tehran and Damascus, Washington must respond firmly, lest inaction lead to further challenges and possible miscalculation.
Fourth, predictable U.S. responses make it easier for Tehran and Damascus to calibrate risk and reduce the costs of testing American limits. U.S. responses should therefore be unpredictable and should target assets that Tehran and Damascus truly value to introduce uncertainty into their cost-benefit calculus and to exact an unacceptable price for their policy choices.
Fifth, the best way to counter Iran's proxy strategy in Syria is through a U.S. proxy strategy involving a revitalized train-and-equip program for non-Islamist Syrian rebels. This would enable the United States to pressure Tehran and Damascus by indirect means. The goal would be to mire pro-regime forces in a low-level insurgency in areas they currently control; hinder new offensives against rebel-held areas in the east, the south, or Idlib province while reducing the potential for Iranian troublemaking elsewhere in the region; and disrupt Iranian efforts to build a land bridge to the Mediterranean Sea.
Sixth, Washington should consider cost-imposing measures vis-à-vis Iran elsewhere in the region, such as Yemen, to make its intervention there more costly and further stress its overstretched forces. This might reduce Tehran's willingness to challenge U.S. interests in Syria.
Finally, the United States should strengthen policy coordination with its Gulf Arab allies to prevent unilateral steps vis-à-vis Iran and its allies that could adversely affect U.S.-Iran escalation dynamics in Yemen, Syria, or elsewhere. Indeed, Houthi attempts in October 2016 to target U.S. warships using shore-based antiship missiles indicate that this may have already occurred. It is in America's interest to prevent a recurrence.
Michael Eisenstadt is the Kahn Fellow and director of the Military and Security Studies Program at The Washington Institute.