Assuming China forcefully occupied the Senkaku islands, what would Japan do? Japan has been building its military capabilities purely for defensive purposes against China and North Korea. Besides, America has a strong military presence in East Asia to threaten Japan’s enemies!
One reason Japan cannot build strong offensive military capabilities is because of its post war pacifist constitution. And it is politically difficult to amend it because most Japanese don’t like war anymore. Their education system teaches them that war is a dangerous thing. Memories of World War Two are still strong.
There are no bilateral talks between China and Japan over the Senkaku Islands. This is because Japan believes there is no reason to discuss anything with China. If the Chinese go to the International Court of Justice (ICJ) at The Hague, Japan says it would not object!
Japan could have built on these Islands about 30 or 20 years ago when they had more advantage. They did not. But now the balance of power has tilted in favour of China. And if Japan builds anything on the Islands now, the Chinese can argue that they have been provoked! So Japan may not convince the world.
The other source of tension in East Asia is the Takeshima (or Liancourt Rocks) islands in the Sea of Japan. They are two pieces of land only 0.2 hectares. A Japanese map from 1779 includes Takeshima islands. The San Francisco peace treaty of 1951 recognised the islands as part of Japan. Even when Japan renounced its claim on the Korean Peninsula, Takeshima was not included as a part of Korea. In 1952 South Korea occupied the islands forcefully and unilaterally drew the Syngman Rhee Line. Japan protested and the USA, the UK, and Taiwan also protested.
When in 2012 South Korean president, Lee Nyung-bak visited Takeshima, Japan protested and suggested they go to ICJ. Seoul refused. Article 33 of the UN charter says disputes should be resolved peacefully but South Korea refuses this route. South Korea put its soldiers on the islands. When Japanese people tried to come there, the South Koreans threatened to shoot them and even killed one Japanese fisherman. Since then Japanese coast guard patrol the area to stop Japanese fishing boats from approaching the islands for fear South Korean soldiers would shoot at them.
Japan has never accepted this South Korean fait accompli. Japan continues to protest against South Korean occupation. Japan’s post war policy of peace means it cannot use force to get them back. In the past Japan has suggested to South Korea to take this matter to the ICJ but South Korea has refused. This is because South Korea has possession, so they don’t need court. There is no much value economically but they have been part of Japan for long. This involves Japanese national pride! If Japan rearms, how will it act?
The third threat comes from the South China Sea. Most of Japan’s natural gas and other raw materials come thru the South China Sea. If it were closed, Japan would be cut off from most of her supplies – about 80 to 90%. So it has a big interest in the South China Sea. But who polices the South China Sea?
There are hundreds of islands and rocks and all of them are disputed between Vietnam, Brunei, Philippines, Malaysia, China and Taiwan.
Before World War Two Japan owned these islands. But after its defeat, it renounced its claims over them. This left a vacuum. Some of them had never been discovered until Japan occupied them. But when it gave them up, they were up for grabs, and are now claimed by everyone.
Japan believes if there is a dispute, the status quo should be maintained as nations seek resolution. However China has now militarised the islands. Previously many of these islands were uninhabited. China has since been reclaiming them and building runaways, hangers (shelters for planes), missile shelters, etc.
President Xi of China had told Obama in September 2015 that China would not militarise the islands. It has since done so and America is not reacting. If the South China Sea is dominated by one country, it will establish that nation’s strategic supremacy in the region. If China controlled the South China Sea and wanted to get Taiwan by force, it would be difficult for the Americans to come in.
China used to have a policy of being soft towards its neighbours as it grew its own economic and military strength. Now that it feels confident, it is beginning to display its might. It has deployed military planes on the islands. In 2018 there was a big leap by deploying jamming systems for radio waves which would intimidate American civil and military planes, they have deployed missile systems and long range bombers (with capacity to carry nuclear weapons) have been landing and taking off for training.