Several weapons could be used to attack tanker traffic in the Persian Gulf or to intimidate oil companies and / or tanker captains to scare them away from their established trade routes through the Strait of Hormuz. An unopposed Iran could use a variety of conventional military means to disrupt tanker traffic, including attacks from surface combatants (repeatedly firing large naval guns at underway tankers, for example) and tactical aircraft (dropping large conventional bombs). In practice, Iran's conventional forces are likely to be overmatched by American and Coalition forces in any conflict over the Strait of Hormuz, so to create a sustained disruption to oil flows, we assume that Iran would use weapons of "asymmetric warfare" such as mines, land-based anti-ship cruise missiles, and small boat suicide attacks.
During the 1990s, Iran acquired three very quiet diesel-electric submarines, and some analysts emphasize their role in a possible Strait of Hormuz disruption scenario. As part of an asymmetric warfare strategy, Iran might use its small submarine force to surreptitiously deploy a minefield. For various reasons, it is less likely that they would use the submarines to launch torpedoes at oil tankers, even though the torpedo threat is the first one to spring to mind for many people who grew up watching movies and reading about the great submarine campaigns of World Wars I and II.