China and Japan have a long and violent history between each other that's resulted in a deep-seated mistrust, and in recent years two of the Western Pacific's greatest powers have been preparing for what would likely be the flashpoint of World War III if it got out of hand.
China and Japan are in a battle of wills over the China Sea that could become a real battle as they build up their militaries, as Defense One wrote in September. But, what would a knock-down fight between Japan and China look like?
China currently has a much larger and stronger military than Japan. It has an active military of over 2.3 million people and a drilling reserve of another 2.3 million. All those troops are equipped with approximately 3,000 aircraft, 14,000 armored vehicles and tanks, and 714 ships.
The Chinese military has also been increasing its military presence in the most likely area that the two countries would fight, the South China Sea. That area of the Pacific is crucial to Japanese trade. Since Japan is an island nation, China could cut off most commercial trade with Japan and force shortages of food and materiel in the country.
But, Japan is no slouch. It could quickly muster over 300,000 fighters to defend the Japanese islands against attack. And it has over 3,500 armored vehicles and tanks with 1,590 aircraft and 131 ships backing them up. While these numbers pale in comparison to China, they're still large enough to mount a strong defense of Japan's homeland.
Unfortunately, Japan's forces likely aren't big enough to maintain open sea lanes and trade routes if China tried to blockade them. But Japan fields a relatively small military because it has an ace up its sleeve: a mutual defense agreement with the U.S.
America acts as a guarantor of Japanese forces, meaning that a protracted war would likely lead the U.S. to join the fight. America boasts the world's most capable military and it is skilled at expeditionary warfare, projecting power across vast seas to far away areas.
If a war broke out in the South China Sea, that expeditionary strength would be vital. The American Marine Corps and Navy would send Marine Expeditionary Units to flash points and strategic priorities. Each MEU contains thousands of Marines — ready to fight tooth and nail — plus the logistics necessary to support them and the armored and air assets needed to protect them.
The Navy would likely dispatch a carrier group to provide additional air support, giving the Marines their capabilities such as increased electromagnetic warfare assets, better surveillance, and a lot more bombs and fighters.
Meanwhile, the Army maintains a 4,000-soldier airborne brigade combat team in Alaska which is capable of airdropping their forces onto strategic islands to reinforce Marines or to establish blocking positions and defenses ahead of predicted Chinese advances.
If called upon, the paratroopers are also prepared for joint, forcible entries. These are operations where the Army and Air Force work together to seize an enemy-held airfield, kill and capture all of its defenders, and then begin using the airstrip for American operations.
The Army had slated the Alaska-based unit — the 4th Brigade Combat Team, 25th Infantry Division — for reduction, but decided to keep the 4th BCT because of increased tensions in the Arctic and potential threats to Japan and South Korea. You know, threats like China.
But China has the defenses in place to make an American intervention costly. First, it has militarized man-made islands in the South China Sea and built mutually supporting bases on them, significantly increasing the costs in blood and ships to an attacker if China has to defend them.
America and Japan would still likely win the war if they decided to fight it, at least for the next few years. But growing Chinese investment in the military, plus constant industrial espionage, is allowing China to pull closer and closer to American strength. So much so that the RAND Corporation has said that a 2025 war could be costly and unwinnable for both sides.
There is some optimism that the war will never take place. While a recent Pew Research Center poll shows that China and Japan still deeply distrust one another, the countries still maintain an extensive trade relationship. Plus, each side is capable enough to make a war too bloody and expensive for the other side to benefit.