Deterring Iranian Provocations at Sea

Since January 2016, surface elements from the Islamic Revolutionary Guard Corps Navy (IRGC-N) have harassed U.S. naval vessels in the Gulf thirty times, 50 percent more than during the same period last year. In each case, the Iranian vessel or vessels approached within weapons range. On at least three occasions, they closed to a distance that could make a collision more likely or could render U.S. ships nearly defenseless to a boat packed with explosive charges. The latest challenges were posed by Iranian harassment of the destroyer USS Nitze in late August and of the coastal patrol boat USS Firebolt in early September.

Incremental erosion by Iranian vessels of the safety zone surrounding U.S. ships and a bias by some U.S. commanders toward restraint have thus created a situation in which Iranian warships are operating at distances that would have been in the past, and should be at present, considered imprudent. This new normal in the Gulf needs to be reversed through a three-pronged approach (detailed below) involving quiet, indirect diplomacy and, when necessary, ship action to restore a wider berth for U.S. vessels. Failure to do so could result in an accident or incident involving U.S. and Iranian naval forces that could adversely affect the broader U.S.-Iran relationship. 

Indeed, the trend lines of U.S.-Iran interactions in the Gulf are heading in the wrong direction, potentially setting the stage for an inadvertent clash. Last year, the IRGC-N tallied three hundred close encounters with U.S. Navy vessels, culminating in a highly provocative rocket launch near the USS Harry S. Truman. In January of 2016, the IRGC-N seized ten riverine command sailors who had strayed into its waters and directly overflew the USS Harry S. Truman with an unmanned aerial vehicle. In the last month, IRGC-N forces harassing four American ships drew so close that their actions created a collision hazard. The USS Squall, a Navy patrol craft, fired warning shots after aggressive IRGC-N maneuvers. 

Ensuring Maritime Safety

Navy commanders are taught that the use of force in self-defense requires the presence of all three components of the "threat triangle": capability, opportunity, and intent. Intelligence, trend analysis, and an understanding of the operating environment help determine whether an adversary has the "capability" to threaten U.S. forces. Incidents like the capture of American riverine sailors and harassment of the USS Squall demonstrate that IRGC-N forces do possess the capability to threaten naval forces in the Gulf. The third element, hostile intent, is more difficult to deduce. U.S. forces use maneuver and warning actions to determine if hostile intent exists by interpreting the reactions of a potential adversary. A commander must attempt to determine intent, deescalate the situation, and prevent the aggressor from gaining an "opportunity" to strike. U.S. vessels use bridge-to-bridge communications, ship maneuver, flares, nonlethal cautionary actions, and warning shots to avoid the use of force while determining if its use is justified. 

Yet guidance to U.S. Navy forces in the region clearly allows, even encourages, defensive action. In guidance to service members from the chairman of the Joint Chiefs of Staff and fleet commander, the language embodied in the chairman's standing rules of engagement is exceptionally clear: all U.S. forces have the inherent right and obligation of self-defense. In December 2015, Vice Adm. John W. Miller, commander of the Fifth Fleet, ordered his forces to plan for aggressive Iranian behavior and be prepared for escalation-of-force measures through execution of warning actions called "preplanned responses." He specifically directed that forces could skip preplanned response steps if time lines become compressed due to an aggressor's closure speed. In his words, the execution of preplanned responses does not require U.S. forces to "absorb the first round" before taking defensive measures. Notwithstanding this guidance, it is rare for a U.S. vessel to engage in a show of force in response to IRGC-N harassment. 

Despite clear legal justification and the commander's guidance supporting a more assertive defensive posture, U.S. naval forces have allowed Iranian forces to close to unsafe distances for two reasons. The first is Washington's overarching desire to improve relations with Iran. A quote from the captain of Riverine Command Boat 802 in the moments before his capture, taken from the command investigation regarding the incident, is instructive. As IRGC-N forces converged on his boat, after it had legally but inadvertently transited Iranian territorial waters, the boat captain expressed these thoughts: "...Ok, what's the commander's intent here, the highest commander's intent, the Commander in Chief would not want me to start a war over a mistake, over a misunderstanding." In this sailor's case, all three sides of the threat triangle were clearly closed. He had the ability and means to escape yet failed to do so, violating the U.S. Navy regulation to repel any search of his vessel.  

Second, ship commanding officers have succumbed to decisionmaking biases that have normalized operations with a closed threat triangle. The "normalcy bias," a refusal to plan or react to a disaster that has not yet happened, and the "pseudocertainty" effect, a tendency to make choices to avoid conflict if the expected outcome is benign, may be to blame. IRGC-N forces approached American ships three hundred times in 2015 without causing a collision, perhaps leading U.S. Navy commanders to mentally categorize such interactions as normal. Against this backdrop, leaders tend to avoid escalatory action to resolve situations that have yet to result in combat.   

Benefits of Greater Assertiveness

Evidence suggests this overly conservative stance may be changing, however. On August 24, the USS Tempest, USS Squall, and accompanying Kuwaiti ships interacted with three IRGC-N Kuch-class weapon patrol boats and one Naser-class patrol boat while conducting a search-and-rescue exercise in international waters. The IRGC-N actions were unprofessional from the start. The trio of Kuch-class boats ignored U.S. attempts to communicate during their approach, and then crossed in front of the coalition formation at six hundred yards. The USS Tempest responded by blasting the ship's horn five times, the international maritime-danger signal. Following this signal, the IRGC-N vessels repeatedly cut across and between the coalition ships in formation. During a forty-seven-minute period, the U.S. ships warned the IRGC-N vessels continuously via radio communications, horn blasts, firing of nine nonlethal "shotcracker" noisemaker rounds, setting of three flares, and use of the Long Range Acoustic Device (LRAD), a nonlethal acoustic warning system. After eight IRGC-N runs toward the American ships, the USS Squall fired three .50 caliber shots across the bow of the lead IRGC-N vessel. Following the warning shots, the IRGC-N vessels halted their approach, loitered approximately three nautical miles behind the formation, and then departed. 

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As already shown, a commanding officer sailing in the Gulf has many options to warn a vessel sailing provocatively. However, once a harassing vessel has closed to the distances the Squall and Tempest experienced, reaction times are greatly reduced and the options available to avoid a clash or collision are restricted.

Conclusions

To reset tolerable risk boundaries, the United States should -- as noted at the outset -- act on multiple tracks. While gestures such as intensified diplomacy are unlikely to persuade Iran to act differently, the U.S. government should make sure governments around the world understand that Washington wants to deescalate and that Iran bears the blame for any incidents that do occur. To that end, the United States should, first, press other countries, such as China and Russia, to urge the Iranians to take up American offers to deescalate.

Second, Washington should engage in a preemptive public diplomacy campaign to indicate that unsafe and unprofessional conduct afloat will no longer be tolerated. Moreover, the United States should renew calls for a hotline between U.S. and Iranian commanders to avert or contain any incident. While past American efforts to propose such a hotline were rebuffed by Iran, this would be yet another opportunity to demonstrate that American forces would rather coexist peacefully.

Third, the U.S. Navy should revise preplanned responses and warnings to permit a more assertive response to IRGC-N harassment. Encouraging commanding officers to take warning action, including warning shots, earlier will reset the boundaries of the U.S.-IRGC-N maritime relationship and may cause Iran to reconsider its most dangerous actions in the Gulf. 

Iranian harassment is best deterred. This end is most effectively achieved through the measured use of live warning shots early in the engagement to compel Iranian ships to stay at safer distances. The USS Squall showed that such deterrence measures can safely and effectively defuse a situation. The response to naval harassment in the Gulf should be overt, assertive, and done early enough to reduce risk while allowing Iranian vessels to safely and honorably disengage, thereby avoiding an incident that could damage the broader U.S.-Iran relationship. 

Commander Jeremy Vaughan is a naval officer and Federal Executive Fellow at The Washington Institute who has completed multiple deployments to the Gulf on a variety of U.S. Navy ships. The views expressed herein are those of the author and do not reflect the official policy or position of the U.S. Navy, U.S. Department of Defense, or U.S. government.