Since the end of the Cold War in 1991 there has been growing pressure from many Japanese and Japanese allies for revisions of the Japanese constitution to allow weapons exports and more cooperation on military matters with allies that Japan depends on for much of its military defense. This is because of post-World War II reforms (and reaction to the military government that got the Japanese Empire into World War II, with disastrous results) that severely restricted Japanese defense policies. The post war constitution forbade Japan from possessing offensive military forces. Thus the Japanese armed forces are called the "Self Defense Forces." It was decades before Japan could even bring itself to build major weapons for its self-defense forces. By the late 1980s Japanese companies found that they were quite good at building quality high tech weapons. At that point, an international marketing survey indicated that, if Japan were allowed to export weapons, they would eventually capture up to 45 percent of the world tank and self-propelled artillery market, 40 percent of military electronic sales, and 60 percent of warship construction. That seemed optimistic, but there was no doubt that the Japanese could produce world class weapons. Throughout the 1990s, Japanese manufacturers produced nearly $7 billion worth of weapons a military equipment a year, just for the self-defense force.
Efforts to actually revise the restrictive constitution have been revived periodically since the 1990s. But the pressure to revise has been relentless in large part because of the growing military threat from China and North Korea (and, to a lesser extent, Russia). It got to the point that the United States threatened to withdraw from key provisions of a mutual-defense treaty that long seemed to guarantee Japan American military protection. The U.S. wanted Japanese troops to be ready and able to help their American counterparts in combat and many Japanese insisted their constitution did not allow that sort of thing. That thinking has been changing as the Chinese threats increase and the risk of Japanese and Chinese forces actually fighting become very real.
Meanwhile local and foreign military analysts began to note that while the Japanese air force and navy seemed quite competent and well equipped for combat, the same could not be said for Japanese soldiers. Some 60 percent of the Japanese forces belong to the army and compared to the navy and air force the personnel are not as well equipped or trained. Most of the money has always gone to the navy and air force because the American strategy was destroy any invaders before they reached Japanese territory and the Japanese were fine with that. The air force aircraft flew constantly and the pilots and ground crews became quite proficient. Same with the navy, which kept its ships at sea a lot and trained hard even under harsh conditions. This was a naval tradition in Japan and it paid off, as it did in the early days of World War II.
But starting in 2004 Japanese soldiers got more and more involved overseas in non-combat peacekeeping operations. Technically this violated the constitution but the growing pressure to improve the military and maintain essential military alliances allowed the operations to continue, proliferate and eventually some Japanese ground troops (mainly airborne and commando) actually got involved, often unofficially, in combat. The performance of Japanese weapons and soldiers under fire provided proof that Japanese ground forces needed some major changes if they were to perform adequately in a confrontation with a better armed and organized foe. Many Japanese army officers, especially those who have gone overseas for training, peacekeeping duty or as observers to other wars, developed a long list of needed changes. Many of them were quite basic.
Take for example firearms. At the end of the Cold War Japanese troops were still armed with the Type 64 rifles. This was Japanese equivalent of the American M-14, a 1950s design that was replaced in the 1960s by the M-16. In 1989 the new Type 89 rifle entered service. It was a decent variation on the American M-16 but when it first saw action in a combat zone over a decade later the troops noted numerous deficiencies. Worse, not enough Type 89s were ever produced to equip all Japanese troops leaving many Type 64s in service.
It was also noted that the Japanese special operations troops followed the example of their American counterparts and somehow obtained needed accessories for their weapons, often with troops paying for it themselves. The Japanese Ministry of Defense saw that and allowed and encouraged Japanese infantry to buy needed accessories (especially new sights) for their Type 89 rifles as well as any other new gear they felt would help them in combat. Eventually that led the government to pay for the development and purchase of a new generation of combat gear for the infantry, often based on what the Americans and South Koreans are using.
Meanwhile other changes have already taken place. In 2012, for the first time since World War II., Japan deployed warplanes under the "self-defense" provision of their pacifist constitution. Article 95 (of the Self-Defense Forces Law) allows Japanese military forces to deploy warships and warplanes to defend each other. And that is what Japan allowed its commanders to do as the Japanese Navy send Aegis equipped warships out to possibly shoot down a North Korean planned "satellite launch" (which was seen as a violation of a recent North Korea agreement to halt its nuclear weapons and ballistic missile program). Japanese F-15s also flew out to protect the Japanese Aegis destroyers. These ships carry missiles capable of intercepting ballistic missiles, or low orbit satellites. The Aegis radar system can locate and track these targets. Japan deployed three Aegis equipped destroyers for this mission, two in the East China Sea (south of South Korea) and one in Sea of Japan (off the west coast of Japan). The F-15s were prepared to fire warning shots, or shoot down, aircraft trying to interfere with the Japanese destroyers. The Japanese did not have to open fire but it was not lost on North Korea and China that the Japanese were quite prepared to.
The reforms extended to many rather mundane aspects of military life. For example in early 2016 Japan finally agreed to replace its canned combat rations with the plastic pouch (MRE, Meal Ready to Eat) system pioneered by the United States. Japan was the last holdout for canned combat rations in East Asia. China, South Korea and Japan, the three most powerful (in terms of numbers and quality of weapons and equipment) armed forces in East Asia have all been borrowing ideas from the United States, which is considered to have the more advanced weapons and equipment on the planet. For decades Japan got the new weapons but stubbornly clung to the use of canned combat rations. Partly this was due to love of tradition, partly because the Japanese, like most East Asians, are very serious about food and partly because of their post-World War II constitution Japanese troops were forbidden to get involved in wars or peacekeeping operations overseas. Without real combat zone experience there was no realistic examples of how superior MREs were to their older canned counterparts. But now prohibitions against sending troops overseas are being eased and a younger generation of troops prefer the convenience of MREs, which many have already discovered because MREs are popular worldwide with those who hike or go camping. There were cultural and historical factors at play here as well. During World War II Japan, although still a poor country by Western standards, had the most modern armed forces in East Asia. Although defeated, Japan continued to honor the sacrifices of its veterans (and ignore the many war crimes they committed against non-Japanese). One of the most notable sacrifices was food. Especially for Japanese troops who served in the Pacific while most were in China) the eventual American dominance of the waters between Japanese held islands meant a lot of Japanese troops got very hungry. Actually over half a million died from starvation or malnutrition. The survivors returned home to a devastated economy and went hungry for another decade along with most other Japanese. But by the 1970s the economy began to take off and superior food became a national obsession. This was especially true in the new Japanese military where the government and the voters did all they could to see that soldiers and sailors had the best food possible. That played a large role in tolerating canned combat rations for so long. But eventually practicality prevailed in the military and changed just about everything.