The Straits of Hormuz: Strategic Importance in Volatile Times
Guzansky, Yoel
INSS Insight No. 204, September 3, 2010
www.inss.org.il/publications.php?cat=21&incat=&read=4387

Iran's oft-sounded threats to close the Straits of Hormuz to international
shipping and thereby stop the flow of Gulf oil seem to have increased in
frequency and intensity, apparently in light of the decision to impose
harsher sanctions against Iran. Senior Iranian officials have thus warned
that "any act of aggression or adventure" - in practice this means
inspections of cargoes of Iranian ships (a step included in the Security
Council resolution on Iran) - would generate an "appropriate" Iranian
response and turn the Straits into an unsafe place for Iran's enemies.

In general, these pronouncements are designed to deter the international
community from fulfilling its resolutions and raise the cost of any military
confrontation with Iran. The former commander of the Revolutionary Guards
naval force, Rear Admiral Morteza Safari, warned that "American warships are
easy prey to the Iranian navy," and that for the "over 100 foreign naval
vessels" currently in the Gulf, Iran would sail "100 vessels of its own."
Despite the fact that similar threats have never been realized in the past,
it is important to examine possible scenarios, as the Straits are a choke
point of critical significance for both regional and global stability.

The Straits of Hormuz are considered one of the most important naval
passages in the world, and any interference to the flow of oil through them
would immediately affect the global energy market. An overwhelming majority
of the Gulf's oil exports - some 90 percent - go through the Straits. The
American Energy Department estimates that some 17 million barrels of oil -
20-30 percent of global consumption - pass through the Straits daily, in
addition to 20 percent of the world liquid natural gas transports. Every
day, some 15 tankers make their way through the Straits, most of which are
headed for the Asian markets (e.g., over 75 percent of Japan's energy
consumption comes from the Gulf).

The oil moves in tankers through the Straits, whose narrowest point is 33
km. The tankers move into the Gulf in a 3.2 km-wide shipping lane, with a
lane of equal width for outgoing traffic (a 3.2 km wide no-traffic lane
separates the two active ones), so at no point does the total width of the
international crossing exceed 10 km. The international shipping lane at the
entrance to the Gulf is in Oman's territorial waters but farther up the
tankers enter an area that Iran claims as within its sovereignty.
Accordingly, it would be relatively easy to interrupt naval transportation
to and from the Gulf.

Even in the unlikely possibility that Iran could seal the Straits
hermetically over a long period of time, such a move is not in Iran's own
best interests, as it would interfere with the import of refined oil to Iran
and Iran's export of crude oil (representing some 80 percent of its income)
and would almost certainly lead to a confrontation with the American navy.
Therefore, Iran has never attempted to block the Straits, certainly not
fully. Operationally, such a move would require extensive naval mining in
the Straits, something Iran found difficult to accomplish clandestinely in
the past and which is tantamount to an act of war. At the end of the
Iran-Iraq War, Iranian attacks on naval vessels generated an American
response, whereby American navy ships escorted Kuwaiti oil tankers to and
from the Gulf. In another case, after an American frigate hit an Iranian
naval mine, the United States launched Operation Praying Mantis, during
which the American navy sank most of Iran's usable naval forces in the Gulf,
putting them permanently out of commission.

Because of the Iranian navy's weakness and America's military superiority in
the Gulf, Iran has placed priority on acquiring and building a large number
of small, fast-moving vessels (some of which are for unmanned use) and has
re-outfitted civilian vessels for military missions. As a result, in recent
years there have been reports of Revolutionary Guard naval vessels
skirmishing with American vessels. In January 2008, Iranian boats approached
American vessels in a threatening manner, using the so-called swarm tactic:
many small, fast-moving boats, some laden with explosives, intend to attack
the target simultaneously from different directions (together with support
from air and land fire) in order to stun the enemy's defensive systems and
limit the enemy's capacity for responding effectively.

Recent assessments indicated that the American 5th Fleet is capable of
opening the Straits to naval vessels within a week. Such assessments may be
based on the fundamental weakness of the Iranian air force, a belief in the
American capability of paralyzing Iranian positions near the Straits, the
US' improved ability to remove naval mines, and the fact that the Straits
are deep and wide enough not to allow them to be easily blocked. In
addition, unlike other vessels such as cargo ships, tankers are hard to sink
due to their size, structure, and the nature of crude oil. Nonetheless,
senior American military sources express themselves with caution: "Iran is
developing its conventional military with 'limited' offensive missiles and
naval assets able to disrupt Gulf shipping," and it "has the ability to
restrict access to the Straits of Hormuz with its naval forces temporarily
and threaten U.S. forces with missiles."[1]

Moreover, new Iranian means and improved tactics may present a more
significant challenge to the American navy. As early as 2008, Iran already
announced that it was building new bases, which could threaten movement
through the Straits. The Iranians may also have introduced new types of
vessels into service, such as mini-subs and improved weapons based on
asymmetrical tactics.

Any American attempt to open the Straits would require at least partial
removal of naval mine fields and dealing with the Iranian shore-to-sea
missiles. Moreover, since such a confrontation is liable to develop into a
more widespread campaign, questions arise regarding the West's ability to
limit the confrontation in time and space. For example, it may be that in
tandem with an Iranian blockade of the Straits there would be an attack on
the western shore of the Gulf, where there are strategic infrastructure
facilities such as ports, refineries, and desalination plants.

Even in a more optimistic scenario (a partial blockade of the Straits with
rapid, effective international action to open them), the impact of a
"limited" campaign on the global energy market is liable to last a long
time, beyond the event itself, because of the concern about a lack of
supply. A longer event might necessitate the use of strategic reserves,
taking advantage of the redundancy of global manufacturing capabilities
(greatly limited because it is primarily concentrated in the Gulf region)
and using alternate shipping routes such as the Saudi pipeline moving oil
from the Gulf to the Red Sea (5 million barrels per day) and the
Habshan-Fujairah pipeline, which is supposed to start operating next year
and ferry 1.5 million barrels per day from the Gulf daily.

The Iranians apparently prefer to focus on harassment, i.e., pinpoint
systematic attacks while attempting to cover up their responsibility for the
events (e.g., by using civilian platforms or by acting outside of their own
territorial waters). Because of its fundamental military weakness, Iran is
incapable of blocking the Straits completely for long and will therefore
focus on disrupting the freedom of movement in the Gulf in general, while
attempting to avoid a comprehensive campaign that might cost it dearly -
militarily, politically and economically. Until then, it will continue to
threaten to close the Straits, a move that serves it well even if it is
contrary to its own basic interests, while using the Straits' unique
geographical conditions and global sensitivity to tremors in the world's
energy market.

[1] .Viola Gienger, "Iran Could Get Bomb Uranium, Block Oil, Pentagon Says,"
Bloomberg, April 14, 2010