Thinking about the Straits of Hormuz

Commander Dolan’s May 2012 Proceedings article suggests that the US Navy should respond to potential Iranian aggression in the Straits of Hormuz from a distance, engaging the Iranian navy in the Arabian Sea and IRGC assets in the Persian Gulf from over-the-horizon. He argues that Iranian A2/AD capabilities are such that, in order to conserve the force, the US should not contest the Straits and littoral waters directly; the US navy should instead position its forces to wear down and defeat Iran’s assets from afar. This strategy would potentially mean surrendering control the straits to Iranian forces for a brief period of time but, he argues, would safeguard US ships and provide a more certain method of defeating the Iranians.

While Commander’s Dolan’s ideas are provocative, his analysis does not deal comprehensively with Iran’s most potent capabilities which are difficult, if not impossible, to deal with from a distance.  In addition, if Iran were to close the Straits, even temporarily, alternative oil routes need to be found—and options are limited. While the Habshan-Fujairah pipeline does allow some Emirati oil to bypass the straits, its capacity is less than 9% of the Straits’ daily traffic. Given the limitations of alternative routes, the US navy has focused on confronting the Iranians within the Straits. This brief analysis outlines major Iranian capabilities and the deployments the US has made in an attempt to counter them.

Iran’s primary force in any Straits-closure attempt would be the Iranian Republican Guard Corps Navy utilizing mines, small boats (both torpedo and missile craft), and land-based anti-ship missiles. The Iranian Navy only operates outside the Gulf and poses a significantly smaller threat. Dolan’s article focuses primarily on IRGC-N’s missile threat and, accurately, articulates a standoff strategy to defeat it. The US navy would position guided missile ships and carrier-based planes in the North Arabian Sea to counter land, air, and sea-launched Iranian missiles. However, this strategy only deals with the most vulnerable third of Iran’s assets.

Mine warfare could cause havoc in the constricted space of the straights, particularly among merchant vessels. The US Navy is aware of this threat and has deployed 8 of its 14 Mine Counter-Measure (MCM) ships to Bahrain. Additionally, IMCMEX12, the region’s largest ever naval exercise, is currently underway with 30 national navies working together to practice MCM techniques. However, US MCM ships are approximately 20 years old and are limited in number. Their supposed replacement, the Littoral Combat Ship with an MCM unit, has yet to be deployed. Thus, though any attempt by IRGC-N to lay mines would result in the US Navy quickly sinking the mine-laying ships, the resulting minefield would still necessitate a weeks-long clearing process.

 The threat of IRGC small-boat-swarming tactics, armed with both anti-ship missiles and torpedoes, is an equally worrisome issue. These small craft, ranging from inshore patrol boats to coastal fast attack craft, are generally armed with anti-ship missiles (many of Chinese origin) or torpedoes. The US Navy’s response has been the forward deployment of 5 Cyclone-class patrol boats at Manama, with an additional 5 thought to be sent forward within the last 6 months. The US Coast Guard also maintains a permanent presence of 6 patrol boats in Bahrain. However, given the IRGC-N is thought to have anywhere between 75-150 small craft, the US presence is certainly not decisive and could find themselves overwhelmed by sheer numbers. Finally, Iran operates a series of submarines (Qadir-class mini sub and several Russian built Kilo class). US Navy ASW abilities suggest that smaller Qadir-class is the more potent threat to Gulf shipping. However, their short range and questionable combat effectiveness would likely limit their operations to the coastal waters of Iran.

Any attempt by Iran to close the Straits would, therefore, be a combined operation of surface ships utilizing missiles and torpedoes, land-based anti-ship missiles and a mine-laying campaign. This three-pronged approach creates difficulties for a US Navy that has focused on standoff weaponry and large, expensive, high-capability ships. However, this asymmetric conflict design does not mean the US Navy cannot regain the initiative.  By utilizing both existing MCM and patrol ships assets alongside over-the-horizon capabilities, the US can puts itself in the best position to deny Iran the ability to close the Straits.

Standoff weaponry, including carrier-borne aircraft, should be positioned in the Arabian Sea to confront IRIN assets outside the Straits, destroy IRGC-N missile systems, and provide air cover and ASW capabilities inside the Gulf. Meanwhile, MCM ships and USN/USCG patrol boats, alongside helicopter MCM from Bahrain, would be assigned the mission of dealing with IRGC-N small boats and mines. There would likely be losses within this latter group (US Navy simulations in 2011 suggested swarming tactics could sink up to 16 US ships in the Gulf). However, if the US is to remain a guarantor of the free flow of commerce in the region, it must demonstrate a willingness to take on Iran directly and prevent closure of the Straits. This two-pronged response to Iranian aggression allows the US Navy to use its standoff advantages to defeat Iranian A2/AD and static capabilities while at the same time offering an in-situ defense against small boats, mine-laying and ship-borne missile attacks. Maintaining the free flow of commerce through the Straits in the face of Iranian aggression is both extraordinarily important and difficult. For this reason, the US rightly dedicates significant assets both inside and outside the Gulf to ensure Iran is not able to halt the flow of oil.