New realities in the Strait of Hormuz
By David Isenberg
WASHINGTON - For decades, one of the reliable nightmare scenarios for the world
has been the closure of the Strait of Hormuz. In the Cold War era those charged
with coming up with worst-case scenarios would conjure up a southward push by
the Soviet Union to seize control of Persian Gulf oil fields and restrict the
export of oil through the Gulf. In more recent years that threat was
transferred to Iraq and Iran.
Such scenarios caused president Jimmy Carter to famously announce the Carter
Doctrine on January 23, 1980, "Let our position be absolutely clear: an attempt
by any outside force to gain control of the Persian Gulf region will be
regarded as an assault on the vital interests of the United States of America,
such an assault will be repelled by any means necessary, including military
The conventional wisdom is that either country would do so by mining the
strait, something that happened in the war between Iraq and Iran in the 1980s.
The conventional American military wisdom has always been that if a country
attempted to mine the strait it might cause some short-term disruption, but
that US naval assets would clear it in relatively short order.
But a new analysis suggests that the reality is actually more complicated and
less sanguine than conventional wisdom suggests. It finds, "The notion that
Iran could truly blockade the strait is wrong - but so too is the notion that
US operations in response to any Iranian action in the area would be short and
The key question is whether Iran can harass shipping enough to prompt US
intervention in defense of the sea lanes. According to Caitlin Talmadge, a
political science doctoral candidate at the Massachusetts Institute of
Technology, who writes in the current issue of International Security journal,
the answer, especially since the United States has long pledged to keep the
strait clear, is yes.
Talmadge notes that Iran possesses a larger stockpile of missiles and mines 10
times as powerful as those used in the tanker wars of the 1980s, the last
period of sustained naval conflict in the gulf. Even if Iran managed to lay
even a relatively small number of these mines the US certainly would act to
clear the area. But, she writes, "The experience of past mine-warfare campaigns
suggests that it could take many weeks, even months, to restore the full flow
of commerce, and more time still for the oil markets to be convinced that
stability had returned."
Projections based on past instances of US mine-clearing operations indicate
that it could take a month or more to reopen the Strait of Hormuz if Iran were
allowed to initiate even a small mine-laying campaign.
Even worse, if the US decided to clear the strait of mines, the potential for
further military escalation would be high. In part, this is because United
States' mine warfare assets are designed to be used only in non-threatening
Thus, the US would want to locate and destroy any sources of Iranian attack on
its mine countermeasure (MCM) ships. Specifically, it would want to eliminate
Iran's land-based, anti-ship cruise missile batteries. The aerial hunt for
these assets could add days, weeks, or even months to the time needed to clear
the strait, and quickly develop into a large and sustained air and naval
Even if the strait were not closed during such a campaign, military conflict in
the area could cause prices to skyrocket in anticipation of a supply
disruption, and to remain high until markets could be assured that the flow of
commerce had been restored.
Talmadge notes that when Iraq invaded Kuwait in 1990, temporarily halting the
export of oil in both countries, the world price of oil more than doubled
merely on the expectation of future shortages. Although excess global supply
combined with increased Saudi production helped lower the price within a few
months, it did not return to the pre-invasion level for nearly a year.
At a time when excess global capacity is lower and the price of oil is higher,
blockage of the strait would pose a vastly greater threat to the world economy.
In the past, Iran showed restraint, even during the Iran-Iraq War, when
considering whether to disrupt maritime passage in the strait. But if the
United States or Israel attacked Iran, say, over its nuclear program, the
restraint that previously characterized Iranian behavior in the strait might
In terms of assets Iran is thought to be able to lay mines from any of its
three frigates, two corvettes, and 10 fast missile boats. It also has three
ships in the Persian Gulf that appear to have dedicated mine-laying
capabilities, plus three still-functioning mine-laying helicopters. In
addition, Iran possesses more than 200 smaller patrol and coastal combatants
suitable for mine laying. Iran also has three relatively modern diesel-electric
submarines from Russia, which each can carry 24 mines, although the Iranian
operational record with submarines has been spotty.
Iran is believed to possess at least 2,000 mines. Although this is not a large
stockpile by historical standards, even small numbers of mines have been able
to halt surface traffic when their presence was known. Talmadge notes that in
1972 the US immediately stopped all traffic in and out of North Vietnam's
Haiphong Harbor with an initial drop of only 36 acoustic-magnetic mines.
While the exact type of mines Iran has is unknown, it is likely that they have
some beyond the classic contact type. Iran might have the sophisticated
Russian-manufactured MDM-6, which can be delivered by ship or submarine. The
MDM-6 detonates in response to acoustic, magnetic, or pressure influences
within a radius of 50 to 60 meters.
Although it is impossible to predict exactly how many mines Iran could lay
undetected Talmadge thinks it reasonable to assume Iran could lay several
hundred mines in the gulf. She writes:
The effects of the MDM-6 mine on
a tanker are unknown, but given that these mines have both more sophisticated
detonation mechanisms and ten times the charge of the mines that hobbled
tankers in the 1980s, the threat to tanker traffic cannot be dismissed easily.
If shipping companies - and their insurers - believed that large swaths of the
channels and surrounding areas were definitely mined, and in some places with
mines ten times as powerful as what was seen in the tankers wars, they likely
would halt or reduce shipping.
In terms of US efforts to clear
mines, one can only extrapolate from the past. Traditionally, the goal in such
operations is usually to clear an initial passage through a minefield in which
the chance of hitting a mine is believed to be reduced to 10% or less and
through which essential traffic can flow. The problem is that such a route
might not be enough space for full traffic to resume or the oil markets to
Also, the difficulty of clearing mines varies considerably with the type
involved. Moored contact mines can be swept relatively easily once their
location is known. Larger influence mines take more time and skill to identify
and neutralize, often because the ships must carefully mimic the influences
that will cause detonation.
And, as the US Navy plans to develop and deploy airborne mine countermeasures
it is already phasing out its dedicated MCM ships.
Furthermore, such ships might be doing so in the midst of combat, unlike normal
operating procedures. Even the most conservative estimates indicate that Iran
probably possesses at least several hundred anti-ship cruise missiles. Iran
would likely seek to fire them from shore in order to maximize their line of
sight targeting and thus increase their range.
Even after taking into account topographical constraints about half of 33,000
square kilometers constitutes suitable terrain from which to target mobile
missiles against traffic in the strait.
For the US to effectively counter this it would need a concept of operations
for finding and destroying mobile missile batteries and targeting radars across
approximately 16,500 square kilometers - an area about 50% larger than Kosovo.
How long would it take the US to destroy all the mobile batteries? Of course,
estimates depend on assumptions such as the number of missile batteries Iran
deploys, number of daily launches it conducts, and US's ability to locate and
Still, a best-case scenario, assuming a 100% success rate for the US in
locating them, which never happens in real life, would take 18 days. In a less
favorable scenario it could take 72 days to find all the batteries, assuming
the US chose to keep searching, a dubious assumption.
In general, because US detection capabilities depend significantly on Iranian
launches, Iran has some ability to stretch out the hunt.
Talmadge writes that Iran's limitations, such as the command and control and
targeting challenges it would face in littoral warfare, are not often
appreciated. But its strengths are often overlooked as well, such as the stocks
of missiles and much more explosively powerful mines it has acquired since the
tanker wars of the 1980s. She concludes:
Likewise, although the United
States retains the world's best conventional military, its past experiences
hunting mobile targets from the air and conducting MCM operations in the
littorals do not inspire confidence that confrontation in the strait would end
quickly. The United States' fleet defenses have never been tested in combat
against an adversary with large numbers of cruise missiles, and the United
States is in the midst of a major transition in its entire concept of MCM
operations. Given these realities, sanguine assurances about the course and
outcome of military conflict in the strait seem unjustified at best, and
dangerous at worst.
Most important, Iran does not have to seal
the strait entirely to provoke US intervention, and once that intervention
begins, the potential for further military escalation is high. In particular,
if the air and naval campaigns appear to be dragging on, the United States
might be forced to consider holding hostage other targets in Iran or using
ground forces. Either way, a significant and sustained increase in the price of
oil would seem likely.
David Isenberg is an analyst in national and international security
affairs, firstname.lastname@example.org. He is also a member of the Coalition for a
Realistic Foreign Policy, an adjunct scholar with the Cato Institute,
contributor to the Straus Military Reform Project, a research fellow at the
Independent Institute, and a US Navy veteran. The views expressed are his own.