Via Stratfor,
[6]
On June 6, 1944, Allied forces from the United States, United Kingdom and Canada launched the largest seaborne invasion in history by landing nearly 160,000 troops on the beaches of Normandy in a single day. This opened the long-awaited second front in the war against Nazi Germany and started the chain of events that ended in the fall of Berlin in May 1945. D-Day was the longest day in that assault and a pivotal moment of the war. In the intervening period, amphibious assaults have been exceedingly rare. Were one to be carried out today, revolutionary shifts in technology and strategy would make a contemporary amphibious operation radically 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 kilometers per hour (8 miles per hour). 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. 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.
Regardless of technological advances, 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.