Comprehensive amphibious assaults like that which touched off the invasion of Normandy are perhaps the most difficult military operations possible. Defenders are often concealed in strong fortifications while attackers are exposed in open fields of fire along the shoreline. Landings require rigorous planning, detailed intelligence and impeccable logistics. Troops must be well trained, motivated and audacious to storm beaches and airdrop behind enemy lines. And in the end, unpredictable weather conditions can easily derail the whole operation. In nearly all cases, casualty rates are high and failure leads to significant strategic consequences.
For these reasons, amphibious assaults are rare. The last major amphibious landing was Operation Chromite, carried out in September 1950 by Gen. Douglas MacArthur during the Korean War. This decisive assault on Inchon involved more than 70,000 troops and enabled U.N. forces to break out of the Pusan perimeter and recapture Seoul. Much of the equipment used by both sides, however, was not significantly different from that used six years before at D-Day.
Today, the character of an amphibious assault would be quite different. The single most significant difference would stem from the introduction of precision-guided munitions. During the Normandy landings, German defenders used inaccurate artillery such as the 88 mm Flak gun to strike approaching Allied landing craft. A contemporary landing force would approach the beachhead in an amphibious landing vehicle such as the U.S. Assault Amphibious Vehicle, which moves at around 13 kph (8 mph). This would be vulnerable to anti-tank guided missiles fired from positions onshore. On D-Day, ships in the Allied invasion fleet were also able to come relatively close to shore to deploy landing craft. The deadly threat of anti-ship cruise missiles in modern warfare would force a modern fleet to remain farther out to sea, leaving amphibious vehicles even more exposed. Even the insertion of airborne troops farther inland, key to disrupting the enemy and holding chokepoints, is riskier given the advent of surface-to-air missiles, including man-portable air defense missiles, now widely available.
The combination of these factors makes air power absolutely essential. Air superiority or dominance on the part of attackers can both protect the amphibious fleet from enemy aircraft and strike at defenders' precision-guided defenses. They would simultaneously provide indispensable intelligence, surveillance and reconnaissance on targeted positions. On the flipside, the landing force itself can also benefit a great deal on air insertion by helicopter and tiltrotor aircraft.
Challenges to Continued U.S. Amphibious Superiority
Presently, no other nation can match U.S. capabilities in launching a major amphibious operation against entrenched opposition. Advances in defense capabilities, however, have left even the United States struggling to maintain amphibious landing as an option while remaining within tolerable risk parameters.
Part of this challenge stems from a dearth of amphibious landing vessels and associated equipment. Both Adm. Samuel Locklear III, head of U.S. Pacific Command, and Commandant of the U.S. Marine Corps Jim Amos have said the United States does not have the assets needed to carry out a contested amphibious operation in the Pacific Ocean. Such assets include large amphibious ships, vessels to carry the landing force to shore and armored amphibious assault vehicles.
Regardless of technological advance, the art and science of amphibious landing remains indispensable to the U.S. global arsenal.
The United States is struggling to adapt to the advent of precision-guided weaponry and the resulting distance an invasion fleet must maintain from shore. In response, the Marine Corps has introduced a new doctrinal concept called Expeditionary Force 21. The Marines predict that today, invasion fleets should remain at least 65 nautical miles from shore and that this safe standoff range will increase. The solution is to place a growing emphasis on connector vessels and high-speed landing craft that can move rapidly from the invasion fleet to the shoreline to disembark the actual breaching force. The Marines are also looking for a replacement for their slow, aging amphibious assault vehicles. And they are exploring strategies and assets to enhance general amphibious capability, including the greater use of commercial assets such as transport ships and modification of the joint high-speed vessel to give it a role in amphibious landings.
Regardless of technological advance, the art and science of amphibious landing remains indispensable to the U.S. global arsenal. Technology and strategy have shifted over time, but geography remains fixed. Populated littoral environments and strategic islands are still key points of incursion in almost any theater. As seen during the U.S. ground invasion of Iraq during the First Gulf War, there are alternatives to amphibious landings, including land routes, blockades and island hopping, but the United States will need to maintain amphibious capabilities in order to respond to both strategic and political circumstances in the future.