What’s new? Tensions between the U.S. and Iran have repeatedly brought the two sides to the brink of open conflict. While neither government seeks a full-fledged war, a string of dangerous tit-for-tat exchanges amid mounting hostile rhetoric underscores the potential for a bigger military clash.

Why does it matter? Due to limited communication channels between Tehran and Washington, an inadvertent or accidental interaction between the two sides could quickly escalate into a broader confrontation. The risk is especially high in the Gulf, where U.S. and Iranian military vessels operate close to one another.

What should be done? The U.S. and Iran should open a military de-escalation channel that fills the gap between ad hoc naval communications and high-level diplomacy at moments of acute crisis. A mechanism facilitated by a third party might contain the risk of conflict due to misread signals and miscalculation.

I. Overview

The U.S. and Iran have come perilously close to full-fledged military conflict thrice in the past eleven months. The tensions emanate from the Trump administration’s “maximum pressure” campaign against Iran and Tehran’s “maximum resistance” response, both triggered by the U.S. decision to withdraw from the nuclear deal and reimpose economic sanctions. Neither side appears to be seeking a war, but both have heightened the risk of one by engaging in provocative acts with little ability to communicate. As illustrated by President Donald Trump’s 22 April threat to “shoot down” any Iranian boat harassing U.S. ships, the danger may be greatest in the Gulf and Strait of Hormuz, where oil tankers and naval vessels help clog the sea lanes. The adversaries’ incapacity to communicate instantly when incidents happen opens the door to unintentional escalation if one side misreads the situation and, as a result, miscalculates. Establishing an operational channel, facilitated by a third party such as Oman, could minimise risks of such a scenario. If successful, a mechanism of this type could be replicated in other regional flashpoints.

Neither side appears to be seeking a war, but both have heightened the risk of one by engaging in provocative acts with little ability to communicate.

Facebook Email



This briefing outlines the need for a U.S.-Iran de-escalation channel and identifies its key elements. It is based on nearly three dozen interviews with current and former U.S., European, Omani and Iranian officials with experience operating in the Gulf and familiarity with past efforts at military-to-military communication between the U.S. and its adversaries, including, most recently, the U.S.-Russia deconfliction line in Syria and channels to the Popular Mobilization Units (PMUs) during the counter-ISIS campaign in Iraq.

II. Treacherous Waters

U.S.-Iranian frictions have been growing since the Trump administration’s May 2018 decision to leave the Joint Comprehensive Plan of Action (JCPOA) and reimpose sanctions. The risks rose again a year later, when the U.S. revoked sanctions exemptions allowing Iran’s remaining customers to import its oil and Tehran began responding with nuclear and regional escalation. The dynamics of “maximum pressure” and “maximum resistance” have brought the two sides to the brink of war three times: first in June 2019, after Iran shot down a U.S. drone; then that September, when Iran stood accused of attacking Saudi Arabia’s oil infrastructure; and again in January 2020, when the U.S. killed General Qassem Soleimani, triggering retaliatory Iranian missile strikes in Iraq. The COVID-19 pandemic could have opened a window for a ceasefire but instead appears to have become an occasion to display hardened positions. With neither side willing to yield, no effective communication channel and an arc of flashpoints where the U.S., Iran and their respective allies are juxtaposed, a single incident could spin out of control.

The Gulf, in particular, is an arena where even a minor skirmish could easily spark an unintended conflict. Such a scenario nearly played out on 20 June 2019, when Iranian forces shot down a U.S. Global Hawk drone that Tehran claimed, contra Washington’s denials, had entered Iranian airspace. The incident came close to prompting retaliatory U.S. airstrikes on the Iranian mainland. Less than a month later, on 18 July, the USS Boxer, an amphibious assault ship, downed an Iranian drone in the Strait of Hormuz. President Trump described this action as “defensive”, saying the drone had come within 1,000 yards of the U.S. vessel, reportedly failing to respond to repeated warnings. Tehran denied the loss of any aircraft. These incidents, occurring against the backdrop of Iran’s suspected involvement in several attacks from May to September 2019 on international shipping and Gulf energy infrastructure, prompted the U.S. Central Command (CENTCOM) to announce on 19 July that it would launch Operation Sentinel to “increase surveillance of and security in key waterways … in light of recent events”.

The huge number of warships from many countries in the narrow Strait of Hormuz increases the odds of a mistake.

Facebook Email



Since late February 2020, other stakeholders in Gulf security, including European states, have also deployed vessels to the Gulf to monitor and de-escalate tensions. One such deployment is the European-led Maritime Awareness in the Strait of Hormuz (EMASoH) mission. As a result, one of the narrowest chokepoints in the world, through which roughly one third of the world’s seaborne oil passes daily, is crowded with both civilian and military vessels. The dense traffic increases the risk of accidents. Oman’s foreign minister, Yusuf bin Alawi bin Abdullah, warned in February: “The huge number of warships from many countries in the narrow Strait of Hormuz increases the odds of a mistake. Our message to all our friends … is to be cautious”.

These risks are even higher regarding interactions between Iranian and U.S. military vessels amid growing tensions between the two countries. A former U.S. official said: “When we and the Iranians operate in the Gulf, it’s like two people in a phone booth”. As part of its Operation Sentinel, the U.S. directs observation and rapid-reaction forces, including vessels and aircraft, to respond to incidents involving U.S., commercial or third-party state vessels. From its side, Iran, which rejects any U.S. claim to having a legitimate military presence in the Gulf, has spoofed bridge-to-bridge communications and jammed vessels’ GPS signals.

U.S. officials also assert that Iranian fast attack craft persistently provoke both commercial and military vessels in the area, including most recently on 15 April 2020 when eleven Islamic Revolutionary Guard Corps (IRGC) navy speedboats harassed a formation of six U.S. warships in the Gulf, at one point coming within ten yards of a collision despite radio warnings and horn blasts. The U.S. forces were undertaking “joint integration operations” between ships and attack helicopters as part of a series of exercises, some including live fire, that began in March. Following the incident, Trump announced that he had “instructed the U.S. Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea”. The IRGC rejected the U.S. version of what transpired on 15 April, contending that it was the U.S. vessels that had carried out “unprofessional and provocative actions”. Too, the IRGC maintained that it had “in recent weeks … witnessed the recurrence of unprofessional behaviour” by U.S. forces and “increased the capacity of its naval patrols” in response.

The existing communications infrastructure in the Gulf is insufficient to limit prospects of miscalculation or escalation. As the U.S. Air Force chief of staff, General David Goldfein, noted, “there is no deconfliction hotline nor any communications between the U.S. military and Iran, except for safety of operation radio calls on guard at the tactical level”. In other words, save for routine messages between ships in proximity, the U.S. and Iranian militaries do not talk to one another. These tactical, ad hoc communications between Iranian and U.S. vessels (“bridge-to-bridge communications”) leave officers of limited authority in charge of preventing unintended confrontations and containing them if and when they occur.

These deficiencies are compounded by the absence of institutionalised indirect lines of U.S.-Iran communication, apart from a Swiss diplomatic channel that links the two sides at senior levels. The latter channel allowed the U.S. to promptly convey red lines to Tehran after it killed the IRGC Qods Force commander, General Soleimani, for example, and permitted Iran to confirm receipt of and respond to U.S. messages, thus helping stop a dangerous situation from escalating further. Because the channel was designed for diplomatic, not military, communication, however, it may not prevent an incident during a standoff between military ships from turning into a shootout.

The Swiss diplomatic channel may not prevent an incident during a standoff between military ships from turning into a shootout.

Facebook Email



In an incident during the Obama administration’s second term, in 2016, the IRGC detained ten U.S. sailors travelling aboard two riverine boats from Kuwait to Bahrain but that drifted into Iranian territorial waters. Then-Secretary of State John Kerry, who over the course of JCPOA negotiations had developed extensive direct contacts with his Iranian counterpart, was on the phone with Foreign Minister Javad Zarif within 30 minutes of learning of the incident, and the two spoke “at least five [times] … over a period of roughly ten hours”. Iran released the boats and crew the following morning. Amid the current acrimony, when direct interaction between senior diplomats is scarce, Washington and Tehran would be unlikely to open a direct diplomatic channel in a moment of crisis. Furthermore, the U.S. blacklisted Zarif in 2019. While Twitter has provided an unusual means of direct communication and signalling between key officials on both sides, it is hard to see such a public platform being effective in preventing inadvertent escalation.

Even before the present round of U.S.-Iran tensions which began in 2018, senior U.S. defence officials recognised the risks posed by the lack of an operational channel situated between tactical, bridge-to-bridge and strategic, diplomatic communications. They advocated establishing a channel that could help avert a misreading of signals between the U.S. and Iranian militaries. Recognising this same dangerous potential for escalation, the U.S. Congress in December 2019 required that the executive branch submit a report on deconfliction channels with Iran. As of mid-April, the Trump administration had yet to do so.

III. Anatomy of a De-escalation Mechanism

While a U.S.-Iran de-escalation mechanism can draw on past U.S. experiences with military communications links with adversaries, including the Soviet Union, China, Russia and Iran-backed Iraqi paramilitary groups, it will require some innovation. In the absence of a U.S.-Iran Incidents at Sea agreement, such as the U.S. had with the Soviet Union, the two sides have limited means of keeping their respective naval forces separate through mechanisms such as “deconfliction lines” or “ops boxes” (temporary zones of exclusive operations). Also unlike past cases, diplomatic communication lines supporting operational information exchanges between U.S. and Iranian personnel are few and far between, and the legality and feasibility of direct contact between the U.S. and Iranian militaries may be complicated by their reciprocal designations of the IRGC and CENTCOM as foreign terrorist organisations.

Efforts to establish a direct communication channel would also almost certainly encounter significant hurdles in Tehran and Washington. The Iranian military, the IRGC in particular, was reportedly instrumental in undermining the Obama administration’s 2011 attempt to set up a high-level military hotline between the two governments, both for fear of being perceived as legitimising a U.S. military presence in the region and due to Supreme Leader Ayatollah Ali Khamenei’s disdain for President Mahmoud Ahmadinejad, who reportedly favoured the idea. Too, the Trump administration’s coercive approach has dulled the appetite in Tehran for any sort of diplomatic engagement under duress. As an adviser to Ayatollah Khamenei put it:

The Trump administration has already reneged on the only agreement [the JCPOA] we had between the two countries in 40 years, has waged an all-out economic war against our nation, has assassinated our most popular general [Soleimani], and has not even agreed to loosen sanctions amid the COVID-19 crisis. Instead of thinking about a hotline, they should try to build some trust. Establishing a hotline would then be technically straightforward and easy to implement.

One should expect resistance in Washington as well. There, policymakers are sceptical both because they believe that Tehran would reject any U.S. proposal and because they are reluctant to engage Iran even on operational matters for fear of undercutting the pressure campaign with mixed messages. These factors may limit possibilities for even an indirect military communication channel.

A U.S.-Iran de-escalation channel would have to anticipate a number of potential problems.

Facebook Email



Overcoming these obstacles will be challenging, especially given the wider diplomatic impasse and distrust between the two sides, but it is important to try. Since both leaderships seem keen to avoid uncontrolled escalation, the imperative of avoiding unintended conflict may conceivably take precedence over other duelling considerations. The most feasible structure for a U.S.-Iran de-escalation channel arguably would be for third-party intermediaries to link counterpart U.S. and Iranian officers of higher rank and authority, and on a more structured basis, than existing bridge-to-bridge communications.

Such a mechanism would have to anticipate a number of potential problems. For example, communication through an intermediary could become an unwieldy “telephone game”, especially if exchanges were to occur between officers of mismatched rank and authority. Factions within the U.S. and Iranian governments could also seek to undermine military-to-military communications within each side’s respective interagency process. Local commanders suspicious of the other side’s intentions might withhold vital information from their opposite numbers and officers might be hesitant to risk their careers by appearing amenable to cooperation with an arch-adversary.

That said, at least during the initial stages, an indirect, mediated de-escalation mechanism could make contacts more politically palatable for both parties. Being limited in scope and ambition, it would require no dramatic departure from the Trump administration’s “maximum pressure” approach. Nor would it entail Iran endorsing a U.S. military presence that it rejects as a matter of principle. But it would provide a safety valve that could prevent inadvertent escalation. Indeed, some former and current officials in Tehran and Washington suggest that, at a minimum, both governments would view the prospect of a mediated hotline with interest, given the present level of tension.

The first step toward establishing an indirect channel is to identify a viable third-party intermediary. The ideal candidate would combine deep expertise in Gulf navigation with experience in mediation and constructive diplomatic relations with both the U.S. and Iran. Based on these considerations, Oman would be a particularly strong candidate. It manages security for ships exiting the Strait of Hormuz into the Gulf of Oman, and as a result has technical acumen and expertise in relaying communications. It has previously facilitated U.S.-Iran communication. And both sides have typically considered it an honest broker. Oman has a military cooperation agreement with the U.S., and jointly operates a military commission with Iran. It has held separate joint exercises with the Iranian and U.S. militaries, most recently in April and September 2019, respectively. Omani officials have expressed interest in facilitating military-to-military communications as an intermediary between the U.S. and Iran as long as both sides ask for it.

Omani officials have expressed interest in facilitating military-to-military communications.

Facebook Email



European or other extra-regional third parties may not be as effective as Oman due to a lack of trust between Iran and U.S.-allied European powers with forces deployed to the region. Within the region, intra-Gulf Cooperation Council sensitivities may discourage other GCC members from offering themselves as a third party. Alternatively, the UN could appoint an observer based in the region to act as an intermediary or establish a mechanism for monitoring Iran-U.S. communication and mediating in case of an unintended clash. The UN has extensive experience across a broad range of conflicts facilitating links or providing intermediaries between adversaries. Yet Iran appears to have greater appetite for dealing with a national government than with an international organisation. The UN may also have insufficient access in Tehran to get in touch quickly with the military’s upper echelons.

The second element relates to the rank, authority and specialisation of the persons on each side responsible for managing the communication channel. In the best-case scenario, they would be high-ranking officers with direct access to both the most senior in-theater commanders and decision-makers in their respective capitals, and the ability to manage communications without a large support staff. They should occupy the rank of colonel or higher, whether in a U.S. combatant or component command or in Iran or Oman’s General Staff. It might be wise to build multiple layers of contacts between officers of ascending rank and authority, so that during escalating crises intermediaries can quickly work up the chain of command. In one possible design, a one-star general in CENTCOM’s leadership would communicate by telephone with an Omani general maintaining a separate telephone line with a counterpart on the Iranian General Staff.

Critics of such a mechanism may contend that, owing to rancour between Tehran and Washington, establishing even a line of contact for operational de-escalation is likely to encounter insurmountable political opposition. They may also say it will prove ineffectual even if established. Although the critics could be right, high-ranking current and former Iranian and U.S. officials have told Crisis Group that they believe this mechanism is both needed and viable, and that the mechanism’s potential to prevent a catastrophic miscalculation and inadvertent escalation outweighs its costs and risks, even if its remit is limited.

At a time when neither side is likely to deem direct links appropriate yet both want a means of de-escalating at dangerous moments, use of an intermediary such as Oman could help reduce tensions and build confidence in the mechanism without limiting either party’s room for manoeuvre. Indeed, if it works, the mechanism could be developed into a direct channel – without requiring changes to broader policy – and replicated in other theatres. In a future less beset by mutual antagonism, such a communication channel might even help undergird a U.S.-Iran Incidents at Sea agreement.

Use of an intermediary such as Oman could help reduce tensions and build confidence in the mechanism without limiting either party’s room for manoeuvre.

Facebook Email



IV. Conclusion

Establishing a U.S.-Iran de-escalation mechanism would be an insurance policy against accidental eruption of conflict. Like the Swiss channel, which in January 2020 underscored the value of having clear lines of contact in anticipation of or in response to incidents with escalatory potential, and ongoing bridge-to-bridge communications, this additional mechanism would serve both sides’ interest in managing their standoff. It would also serve a useful force protection role without requiring political concessions or a shift in strategic posture. Even amid tit-for-tat military exchanges, the mechanism would allow the two sides to take action to avoid missteps that would broaden the conflict into a war neither appears to want. Intermediaries, such as Oman, can play an important role in setting up a communications mechanism of this sort, initially focused on the Gulf region. Over time, if it proves its worth, it could be upgraded to become a direct channel and be replicated in other flashpoints.

The U.S. and Iran are likely to have an acrimonious relationship as long as the underlying tension between “maximum pressure” and “maximum resistance” lingers – and perhaps well beyond that point. But in the absence of a major diplomatic breakthrough, an indirect military communications channel could go some way toward ensuring, at least, that a single incident will not spark a wider conflagration.

Washington/Tehran/Brussels, 23 April 2020