Smooth Sailing: The World's Shipping Lanes Are Safe
Most of these countries rely on the safe transport of oil through one 21-mile-wide waterway: the Strait of Hormuz, which leads out of the Persian Gulf into the Indian Ocean and through which 16.5-17.0 million barrels of oil were shipped daily in 2004 (accounting for nearly 25 percent of global oil shipments). Oil bound for China, Japan, and the West Coast of the United States from the Middle East must also transit the Strait of Malacca and the Strait of Singapore, both of which carried 11.7 million barrels per day in 2004. These passageways are the chokepoints where the potential for the disruption of tanker traffic by terrorist attacks or naval blockades is greatest.But in reality the risks to maritime flows of oil are far smaller than is commonly assumed. First, tankers are much less vulnerable than conventional wisdom holds. Second, limited regional conflicts would be unlikely to seriously upset traffic, and terrorist attacks against shipping would have even less of an economic effect. Third, only a naval power of the United States' strength could seriously disrupt oil shipments, but the United States is more likely to protect shipping on the high seas than to do anything to endanger it. Fourth, if any country attempted to interfere with international shipping, a coalition would inevitably form to keep traffic flowing with manageable damage to oil deliveries and the global economy. Finally, although all-out wars between major powers can seriously disrupt maritime shipping, the chances of such a conflict happening in the foreseeable future are remote.
Mines and conventional-warhead missiles are even less effective now against large modern tankers than they were in the past. During the Iran-Iraq War, several oil tankers ran over mines in the Strait of Hormuz, but they sustained little damage due to their size and the protective effect of the liquid petroleum they carried (petroleum is not explosive in the airless tanks, and its weight holds the hulls in place). Even the most modern antiship missiles have relatively small warheads that are designed to damage the sensors and weapons systems of surface warships but are not capable of sinking or disabling a large tanker. Most missiles shot at a tanker would explode on its large deck, causing minimal damage. Even if they penetrated the deck, they would explode inside tanks where the liquid oil or the water in ballast would absorb the blast without igniting. In order to disable a modern-day tanker, an attack would have to include a salvo of eight to ten missiles with conventional warheads; a sustained campaign would quickly exhaust the missile stockpile of a medium-sized military power.
The greater number of tankers traveling at higher speeds and in more congested shipping lanes makes it increasingly difficult to identify and intercept them. This is especially true for submarines, which have a limited ability to identify surface ships and have only a small onboard supply of torpedoes and antiship missiles. If a submarine attacks a ship using just two torpedoes, it will have exhausted more than a tenth of its standard arsenal. Meanwhile, other potential targets nearby will disperse, forcing the submarine to relocate. A single conventional-power submarine (Iran has only three) facing no opposition could realistically expect to damage about half a dozen oil tankers in a busy sea-lane several hundred miles wide over the course of a month, disrupting at most a tiny fraction of the oil deliveries made during that period. Conventional-power submarines, moreover, are relatively slow and cannot catch modern tankers, which travel at 15-20 knots.
Iran has the capacity to attack the Strait of Hormuz from its shore, using coastal antiship missiles (such as Chinese Silkworm missiles), patrol boats, and short-range aircraft flying from nearby bases. It could also employ small, high-speed boats packed with high explosives to ram oil tankers and hostile naval vessels. But if it ever decided to target ships transporting oil from the Persian Gulf, it would have to interfere with the shipping of many neutral nations. As during the tanker war of the 1980s, a coalition of nations that have an interest in the free flow of oil from the Persian Gulf would quickly form. The United States, with the support of other nations with capable navies and the Persian Gulf states, could neutralize Iran's attacking forces with a combination of actions at sea and attacks against command-and-control facilities, missile sites, ports, and airfields along the Iranian side of the strait. The virtually certain result would be a swift defeat of the Iranian interdiction effort.