By Kris Osborn, Warrior Maven Iran operates an undersea fleet of roughly four to six diesel electric attack submarines armed with weapons, yet very little is known about how many of them may or may not be left. The entirety of what was once Iran’s Navy [https://www.cnn.com/2026/04/14/world/live-news/iran-war-blockade-us-trump] has essentially been destroyed, and there is little doubt that the U.S. Epic Fury attack campaign involved submarines. Much like in the realm of surface and air warfare, there is a massive undersea “mis-match” or “discrepancy” between U.S. Navy Virginia-class submarines and whatever undersea force the Iranians might have, or “have had” before their Navy was destroyed. In the 1990s, Iran acquired three [https://www.foxnews.com/live-news/trump-iran-blockade-israel-war-april-14] Russian-built Kilo-class submarines, boats known to be both quiet and extremely lethal. However, it seems unlikely that Iran sustained any ability to maintain or modernize these boats to the point where they could potentially rival U.S. Navy submarines today. Furthermore, an interesting write up called “Iran Submarine Capabilities” by the Nuclear Threat Initiative [https://www.nti.org/analysis/articles/iran-submarine-capabilities/] explains that Iran’s attack submarines are not well suited to operate in the more shallow waters of the Strait of Hormuz. “Their utility in the Persian Gulf is, however, somewhat limited as Kilo-class boats require a depth of at least 164 feet and can therefore only access about one third of the Gulf.6 Unique water conditions in the Gulf such as water salinity and strong currents further limit the boats’ operational use unless the submarines are deployed to deeper waters in the Gulf of Oman or the Arabian Sea,” the NTI essay states. At one point in recent decades [https://www.cnbc.com/2026/04/15/strait-hormuz-us-iran-blockade-china-india-relations-energy-risk-tensions.html], Iranian officials claimed their military was making progress with nuclear powered submarines, however the NTI assessment posits that it is not believed the Iranians have, had or ever fully acquired this capability. Iranian Submersibles & Mini-Subs The larger threat with Iran’s undersea capacity [https://www.nbcnews.com/world/iran/live-blog/live-updates-trump-blockade-iran-war-hormuz-israel-lebanon-talks-rcna331668], particularly with respect to the Strait of Hormuz, resides in its mini-sub fleet; Iran is believed to operate somewhere between 24-and-30 small submersibles capable of delivering weapons or simply operating themselves as explosives. “The Sabehat-15 GPS-equipped two-seat submersible swimmer delivery vehicle (SDV) — designed by the Esfahan Underwater Research Center—has undergone testing with both the IRIN and the IRGCN,” the NTI essay explains. These SDVs are limited in terms of endurance and payload, so they are primarily intended for mining, reconnaissance and special operations in coastal waters. Therefore, these SDVs are likely to present more of a threat in the Strait of Hormuz than deeper water attack submarines. U.S. Navy Anti-Submarine Overall, Iran’s undersea threat seems somewhat marginal and limited, given that there simply is not any real “mass” to launch a large-scale or sustained attack on U.S. Navy warships. It seems conceivable that a single ship could be damaged [https://www.nytimes.com/2026/04/14/business/strait-of-hormuz-blockade.html], however even that is highly suspect given that warships operate with a host of anti-submarine surface and undersea capabilities. Not only does the U.S. Navy operate a growing fleet of undersea drones capable of conducting reconnaissance patrols along the Iranian coastline, but they also operate surface-driven Variable Towed Array sonar technology. For many years, the U.S. Navy has been operating Unmanned Surface Vessels (USVs) armed with towed sonar, counter mine technology and even offensive weapons as needed. In development for years, these USVs have reached a level of maturity such that they can be quickly deployed in littoral, coastal areas to search for mini-submarines without placing any sailors at risk. These USVs have been quickly progressing with growing levels of autonomy, coordination and multi-domain networking. [https://www.reuters.com/business/energy/us-sanctioned-chinese-tanker-passes-strait-hormuz-despite-us-blockade-data-shows-2026-04-14/] There are also several well-developed aerial anti-submarine technologies in use by the U.S. Navy, particularly with HH-60 SeaHawk helicopters equipped with sonobuoys capable of being dropped below the surface to “listen,” “sense” and “detect submarines.” Advanced sonobuoys are integrated with helicopter integrated command and control able to receive a “rendering” and discern the presence of an undersea enemy submarine. [https://www.cbsnews.com/live-updates/iran-war-peace-talks-us-blockade-irans-ports-day-2/] Kris Osborn is the Military Technology Editor of 1945. Osborn is also President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University
