Anti-Access and Area Denial warfare is the current buzz-phrase, but past attempts by German and Japanese forces could inform modern strategists about its effectiveness.
In the last decade, a new term has been bandied about to describe a seemingly “new” naval strategy: Anti-Access and Area Denial warfare. This strategy, often abbreviated A2/AD, is now a hot buzzword within the halls of the Pentagon and on military blogs.
Despite the jargon, this type of warfare is actually fairly straightforward. Simply put, anti-access and area denial is the strategy of keeping a person from going to a place they really want to get to. Sometimes this has taken the form of walls, or minefields, or even a complex system of fortresses.
What has brought this strategy into the foreground are recent developments in Asia, as China attempts to solidify control over their local waters. Its strategy, based on uniting surface and submarine forces with high-speed anti-ship missiles, is to deny the United States access to Chinese waters and to its coast. Essentially, it is an attempt to turn the South China Sea and the western Pacific into the naval equivalent of a secure fortress. While many observers have decided that this strategy is new, and certainly is for China, similar strategies have been tried throughout history.
But how successful have these strategies been for the nations that employed them? We can answer that by looking at two twentieth-century examples.
The Japanese Pacific Fortress
One example is the Japanese strategy for war with the United States. In 1941, the Japanese were mired in a quagmire on the Asian continent. It couldn’t support its economy, even after the conquests of the 1930s. Strategists in Tokyo realized that Japan was in desperate need for new resources, including rubber, rice, and, most importantly, oil. To get it, they would need to expand into resource-rich Southeast Asia.
The timing for this strike was perfect. After the successful Nazi conquests of 1940 and 1941, the European empires in Asia were either distracted or virtually nonexistent. The time for the southern operation was at hand, and the only obstacle that stood in their way was the United States Navy.
To neutralize this threat the Japanese planned a twin strategy. The first was a sudden initial strike aimed at destroying the American Pacific fleet in port. This was the attack on Pearl Harbor, which was a day that lived in infamy. However, the more important strikes were launched in the weeks after Pearl Harbor in which the Japanese attacked and occupied the Philippines, Guam, and Wake Island, alongside British and French islands in the Southern Pacific. The Japanese goal was to create a system of island forces that stretched from Singapore in the west, around the southern rim of the Pacific, and northward across the central Pacific. These island barriers would effectively create a maritime fortress that could defend against American attacks while the Japanese pursued their goals from within its confines.
How effective was this strategy? Between the summer of 1941 and the fall of 1942, the Japanese succeeded in building their Pacific fortress and took control over American islands across the Pacific from Alaska to Australia. But to continuously reinforce this position against an inevitable counterattack, the Japanese navy continuously pushed the boundaries of its fortress outward until it reached the Island of Midway. There, it was caught exposed and decimated by the US Navy. After this disastrous defeat, the Japanese lacked the resources to counter or block an American attack against the fortress line.
The Solomon Islands campaign also caused the fortress strategy to crumble. Here, American and Commonwealth forces attacked Japanese controlled islands in the South Pacific. The Japanese tried to counter but couldn’t keep the Americans out of their island bastions. Once the Allies established local control over the sea, the Japanese islands, along with their garrisons, were isolated, attacked, overrun, or ignored completely.
This pattern was repeated across the Pacific, and each defeat not only depleted the Japanese forces, but also undermined the fortress system by giving the Americans bases from which to launch new attacks. To Japan’s credit, this large-scale area denial system worked for about a year. But battlefield mistakes and American pressure reduced it to a series of speedbumps along Japan's road to defeat.
The German North Sea Minefield
Perhaps a lesser known example of anti-access warfare is the German's naval strategy before and during World War I. It also offers an excellent example of the difficulties inherent to even a successful defense of a naval perimeter line.
The German naval strategy in the North Sea was built on denying the Royal Navy access to the German coast and territorial waters. Rather than relying on a series of island bases as the Japanese did, the Germans built a series of thick and sophisticated minefields. Ships could only pass in and out of these protected areas through specific channels. The minefields gave the Germans a defended area where could marshal their forces and sail out to challenge the British in the larger North Sea, as they did in the run up to the battle of Jutland.
Unlike the Japanese island barrier, which was porous and broke up quickly after the loss at Midway, the German maritime citadel was never punctured. The minefield successfully blocked any major British action directly against the German coast or the High Seas Fleet stationed within it. It was eventually dismantled after the war.
Although the minefield successfully denied British access to these waters, the Germans still found it difficult to sail out and challenge the British at sea. The minefields were the maritime equivalent of a fortress wall, but the Germans journeying past it to break the besiegers encircling them. Instead, they found themselves bottled up within their defenses, only able to break out in coordinated, but easily countered, attacks.
Meanwhile, the Royal Navy never had much need to penetrate the German fortress. The battle fleet was content to sit and watch for any sally attempt while smaller ships sat at the entrances to the North Sea. This blocked German shipping and strangled the life out of the German economy. When the Germans built their walls, the British simply moved back to the next defensive line and made their stand, while the High Seas fleet was confined by a barrier of their own making.
Lessons Learned from Area Denial Strategies
These examples illustrate the challenges that face practitioners of the area denial strategy. The strategy hands the initiative over to the enemy, as the German's realized with its minefield. By hunkering down behind barrier's for protection, the inside force is stuck in a reactive position rather than proactively influencing developments at sea.
Even when the practitioner of denial tries to act offensively, they run serious risks when they leave the barrier, as the Japanese learned. They succeeded in building a solid speedbump against the US Navy, especially in the central and Southern Pacific, where it took the better part of two years to roll Japanese forces back to their summer 1941 position. However, when they attempted to leave the perimeter to seize another island and destroy the US carrier fleet in the process, the Japanese found themselves exposed and outmatched. The loss suffered in this attempt cost them not just the integrity of the area denial strategy, but the entire war itself. These are strong lessons for any power attempting to adopt their own version of the A2/AD strategy.