The Japanese are an island race, Tim Marshall explains (in Prisoners of Geography: Ten Maps That Explain Everything About the World), with the majority of their 127 million people living on the four large islands that face Korea and Russia across the Sea of Japan and a minority inhabiting some of the 6,848 smaller islands:
At its closest point, Japan is 120 miles from the Eurasian landmass, which is among the reasons why it has never been successfully invaded. The Chinese are some five hundred miles away across the East China Sea; and although there is Russian territory much closer, the Russian forces are usually far away because of the extremely inhospitable climate and sparse population located across the Sea of Okhotsk.
In the 1300s, the Mongols tried to invade Japan after sweeping through China, Manchuria, and down through Korea. On the first occasion they were beaten back and on the second a storm wrecked their fleet. The seas in the Korea Strait were whipped up by what the Japanese said was a “Divine Wind,” which they called a kamikaze.
So the threat from the west and northwest was limited, and to the southeast and east there was nothing but the Pacific. This last perspective is why the Japanese gave themselves the name Nippon, or “sun origin”: looking east there was nothing between them and the horizon, and each morning, rising on that horizon, was the sun.
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The territory of the Japanese islands makes up a country that is bigger than the two Koreas combined, or, in European terms, bigger than France or Germany. However, three-quarters of the land is not conducive to human habitation, especially in the mountainous regions, and only 13 percent is suitable for intensive cultivation. This leaves the Japanese living in close proximity to one another along the coastal plains and in restricted inland areas, where some stepped rice fields can exist in the hills. Its mountains mean that Japan has plenty of water, but the lack of flatland also means that its rivers are unsuited to navigation and therefore trade, a problem exacerbated by the fact that few of the rivers join one another.
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By the beginning of the twentieth century Japan was an industrial power with the third-largest navy in the world, and in 1905 it defeated the Russians in a war fought on land and at sea. However, the very same island-nation geography that had allowed it to remain isolated was now giving it no choice but to engage with the world. The problem was that it chose to engage militarily.
Japan had few of the natural resources required to become an industrialized nation. It had limited and poor-quality supplies of coal, very little oil, scant quantities of natural gas, limited supplies of rubber, and a shortage of many metals.
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It was the thirst for these products, notably iron and oil, that caused Japan to rampage across the far-less developed Southeast Asia in the 1930s and early ’40s. It had already occupied Taiwan in 1895 and followed this up with the annexation of Korea in 1910. Japan occupied Manchuria in 1931, then conducted a full-scale invasion of China in 1937. As each domino fell, the expanding empire and the growing Japanese population required more oil, more coal, more metal, more rubber, and more food.
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This was a massive overstretch, not just taking on the United States, but grabbing the very resources, rubber, for example, that the United States required for its own industry.
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If the terrain had been easier the Americans’ choice may have been different—they might have fought their way to Tokyo—but they chose the nuclear option, unleashing upon Japan, and the collective conscience of the world, the terror of a new age.
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The postwar agreement imposed by the United States limited Japan’s defense spending to 1 percent of the GDP and left tens of thousands of American forces on Japanese territory, thirty-two thousand of whom are still there.
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The 2015 defense budget was its biggest to date, with the yen mostly going to naval and air equipment, including six US-made F-35A stealth fighters. In the spring of 2015, Tokyo also unveiled what it called a “helicopter-carrying destroyer.” It didn’t take a military expert to notice that the vessel was as big as the Japanese aircraft carriers of the Second World War, which are forbidden by the surrender terms of 1945. The ship can be adapted for fixed-wing aircraft, but the defense minister issued a statement saying that he was “not thinking of using it as an aircraft carrier.”
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The military infrastructure at Okinawa, which guards the approaches to the main islands, will be upgraded. This will also allow Japan greater flexibility to patrol its Air Defense Zone, part of which overlaps with China’s equivalent zone after an expansion was announced by Beijing in 2013. Both zones cover the islands called the Senkaku or Diaoyu (in Japanese and Chinese, respectively), which Japan controls but that are claimed by China, too. They also form part of the Ryukyu island chain, which is particularly sensitive as any hostile power must pass the islands on the way to the Japanese heartlands; they give Japan a lot of territorial sea space, and they might contain exploitable underwater gas and oil fields.
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China’s expanded Air Defense Identification Zone in the East China Sea covers territory claimed by China, Japan, Taiwan, and South Korea. When Beijing said that any plane flying through the zone must identity itself or “face defensive measures,” Japan, South Korea, and the United States responded by flying through it without doing so.
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Japan also claims sovereignty over the Kuril Islands in its far north, off Hokkaido, which it lost to the Soviet Union in the Second World War and that are still under Russian control. Russia prefers not to discuss the matter, but the debate is not in the same league as Japan’s disputes with China. There are only approximately nineteen thousand inhabitants of the Kuril Islands, and although the islands sit in fertile fishing grounds, the territory is not one of particular strategic importance.
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Japanese statisticians fear that the population will shrink to under 100 million by the middle of the century. If the current birth rate continues, it is even possible that by 2110 the population will have fallen below the 50 million it was in 1910.
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Even if they do go on to solve a problem like Korea, the issue of China will still be there, and this means the US 7th Fleet will remain in Tokyo Bay and US Marines will remain in Okinawa, guarding the paths in and out of the Pacific and the China seas.
Air Defense Zones often cover areas not part of the defender. For example, Taiwan’s Air Defense Zone includes Chinese air bases on the mainland.