Video Above: How the Navy Will Stop Chinese "Carrier Killer" Missiles

By Kris Osborn - Warrior Maven

(Washington, D.C.) With weapons manned and fully uncovered, swarms of Iranian small boats raced close to, harassed and tried to intimidate a group of U.S. Navy ships transiting the Strait of Hormuz on May 10, prompting the U.S. warships to repeatedly fire warning shots in an effort to diffuse the situation, de-escalate and force the Iranian boats to disperse.

Several U.S. Navy Patrol boats, a Navy guided-missile cruiser and several U.S. Coast Guard ships were escorting a guided missile submarine, the USS Georgia, when they were approached at provocative high-speeds by Iranian Revolutionary Guard Corps Navy boats with, as a Navy report describes it, “their weapons uncovered and manned.”

The Iranian high-speed approaches, which closed within just 150 yards of the USCGC Maui traveling at speeds above 30knots, were conducted by Iranian Fast In Shore Attack Craft vessels.

“After the two IRGCN vessels failed to respond to repeated warnings and closed within 300 yards, Maui exercised lawful de-escalatory measures by firing warning shots. The two IRGCN vessels again failed to respond to warnings and closed to within 150 yards of Maui, at which time Maui fired additional warning shots,” the Navy report describes.

While the Navy report, not surprisingly, referred to the Iranian actions as “unsafe and unprofessional,” reactions among service and Pentagon leaders may have been even more pronounced. Certainly the kind of event is by no means new or unprecedented, as Iran has long been known to operate in this fashion, regularly stopping short of actually starting a lethal weapons engagement.

The narrow Strait of Hormuz is also well known as a high-tension flashpoint close to the Iranian border where large portions of the region's commercial and military shipping traffic travels. The Strait of Hormuz is also known for being an area with high risk for mines and even some kinds of land-fired ballistic missiles.

Apart from simply engaging in harassing or provocative behavior, there does not appear to be a sensible explanation for the Iranian small boat behavior, unless of course the small boat swarming included some kind of serious attack contingency. The strategic aim of a small boat attack would of course be to simply overwhelm ship defenses and deck-mounted guns by approaching in close proximity in a dispersed fashion to “flood the zone” so to speak, and breach the protective perimeter or envelope surrounding a surface ship and it’s close-in weapons ranges with speed and volume.

Although unlikely to cause catastrophic structural damage to larger U.S. Navy ship with small arms fire or missiles, Iranian small boats packed with explosives for suicide bombing missions could present a very serious threat to a large surface ship, depending upon the size and scope of a blast radius. Destroying numerous small boats approaching simultaneously would, it seems, present a kind of ship defense predicament for certain ships such as Navy Cruisers or U.S. Coast Guard ships armed with medium-caliber deck-mounted guns.

However, alongside deck-mounted guns or other weapons, U.S. Navy warships could be armed with Close-in-Weapons-Systems phalanx guns able to fire hundreds of projectiles per minute to blanket areas with defensive fire. A deck-mounted Phalanx, such as the Navy’s current CIWS weapon, would fire hundreds of small steel penetrating projectile rods at approaching small boats, potentially disabling or even destroying them as they seek to approach. CIWS can also blanket a large area and, interestingly, the Navy began a massive fleet-wide upgrade of its CIWS weapons system years ago for the specific purpose of destroying small boat attacks. As far back as 2014, the U.S. Navy began implementing a CIWS 1B variant upgrade which greatly expanded the protective aperture beyond air defense to incorporate surface defenses as well, in part to specifically counter the kinds of small boat threats regularly presented by Iran.

Therefore, upgraded CIWS weapons can now destroy close-in threats that are on the surface and not just coming from the air, a protective technology of great relevance to these kinds of provocation. Should the small boats simply be too fast and too numerous for deck mounted guns or larger munitions to intercept, then a surface-firing CIWS weapon could prevent an attacking small boat from being able to closely approach or penetrate the ship’s hull.

However, the group of Navy ships, according to the Navy report, only included one navy cruiser along with several U.S. Navy and U.S. Coast Guard Patrol Boats. While some Coast Guard Cutters do have CIWS, most of the smaller Navy and Coast Guard PCs do not. Therefore, perhaps the Iranian small boats were extra provocative, at least in part, because they knew they might not have to face CIWS should they approach closer in. Regardless, for a host of obvious reasons, there is little rationale or basis upon which it might appear to make any sense for Iranian fast-attack craft to engage U.S. Navy warships in any kind of serious exchange of fire.

What seems significant about this most recent May 10 incident is that it only included one large U.S. Navy warship, a guided-missile cruiser, and was primarily made up of smaller Coast Guard and Navy Patrol Craft. The ships were guiding or leading the well known SSGN USS Georgia, a guided missile cruiser through the region.

Could the Iranians have actually thought they might be able to succeed in intimating smaller Navy Patrol Craft? Being as they are not larger warships? Certainly they know Navy PCs are armed, however Iranian provocateurs may be less familiar with substantial upgrades the Navy has made to its fleet of PCs in recent years, equipping them with a much greater degree of lethality, weaponry and attack range, in part to address and deter exactly this kind of small boat threat.

In recent years, the Navy has been arming its fleet of PCs with Raytheon-built Griffin B surface-launched, laser-guided missiles able to hit targets at ranges up to 4 kilometers. The idea is to give the 179-foot long, shallow-water PCs the ability to destroy targets at ranges farther than their on-board guns can reach, Therefore, a Griffin-armed PC would be in position to target and destroy approaching Iranian small boats at much greater standoff ranges and with much higher assured destruction.

Extended range offensive firepower is intended to give the PCs enhanced surface warfare technology to position the craft for modern surface and shallow water threats. Laser-guided Griffin missiles, reaching what Raytheon developers describe as "beyond gun range," give the boats an ability to strike threats such as swarming small boats at greater standoff distances. The attack capability enhancements, fortified by advanced sensors, better enable PCs to address multiple threats simultaneously or respond to approaching enemy fire more quickly. The Griffin can provide 360-degree coverage for the ship,

The weapons adjustments are particularly well suited for the Navy's 5th Fleet area of operations which covers much of the Middle East including flashpoint areas such as the Straits of Hormuz; the U.S. Navy is certainly no stranger to these kinds of Iranian provocations in the area, as it is something Iranian small boats have done on multiple occasions.

The Navy upgrades also include unmanned aerial surveillance systems for 5th Fleet PCs, Navy officials said several years ago. This brings the prospect of networking ISR assets with targeting sensors and weapons to improve attack possibilities by relaying targeting information across longer distances. Navy PC boat Mk 52 7.62mm and MK 38 25mm guns are also being upgraded.

The sweeping PC Boat modernization overhaul is intended to extend the service life of the 1990s-era PC boat fleet into the mid-2020s and beyond. The expected service life of a PC is roughly 30-years

The Griffin employs a dual-mode navigational technology using semi-active laser technology and a GPS-aided Inertial Navigation System, according to Raytheon developers.

The weapons upgrade process begins with the installation of the launcher and weapons control system, Forward Looking Infra-Red Systems' BRITE Star II sensor/laser designator, and Raytheon's Griffin B (Block II) missile, Navy officials said.

The 25-foot wide PCs have an eight-foot draft and can reach speeds up to 35 knots. With a crew of 28, the ships are equipped to stay at sea for periods up to 10 days. Many PCs stationed at 5th fleet headquarters in Bahrain are equipped with enhanced communication suites, improved navigation systems and an improved diesel engine control system. They also have two stabilized, electro-optic 25mm gun mounts, Navy data explains. 

-- Kris Osborn is the Managing Editor of Warrior Maven and The Defense Editor of The National Interest --

Kris Osborn is the defense editor for the National Interest. Osborn previously served at the Pentagon as a Highly Qualified Expert with 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.