Very recently, Japanese cabinet approved a change of interpretation of the constitution, which made a broad controversy.
BBC: Japan cabinet approves landmark military change
The article 9 restricts Japan from possessing any army or make use of military force to resolve international conflict. This regulation is famous as a symbol of pacifism. Several Japanese believe that article 9 has protected Japan from being involved in war for a long time.
On the other hand, there is an opinion that article 9 is interrupting Japan to establish a modern nation who has the power to protect the citizens on its own. According to them, the constitution is a symbol of enslavement against the GHQ and the US. They have a strong desire to rewrite the constitution, Prime Minister Shinzo Abe is one of whom.
Actually, the constitution of Japan has never been revised since the enforcement, because its revision is extremely difficult in legal procedure. Instead, Japan government sometimes reinterpreted the constitution, historically. For example, Japan has had the Self Defense Force since 1954. It looks like nothing than an army. However, the existence of the Self Defense Force is not violating the article 9, according to the government.
Now, collective self defense is argued. The Self Defense Force has taken part in peacekeeping operation for many times. However, its field of performance is strictly limited. The Abe administration attempts to widen its availability. It has been demanded by the US, the most important ally of Japan.
It is not surprising that many people are opposed to Abe's decision. A certain man attempted suicide as a protest.
BBC: Japanese man sets self on fire over military rule change
I think his behavior is ridiculous. I never trust a person who underestimates his own life. But it is understandable that some people are concerned about the risk to be involved in foreign war due to this reinterpretation. In contrast, it is not guaranteed that a nation with pacifism would never be attacked by foreign countries.
The international relationships are much more complicated than the past. No matter how we want to be so, we are at risk of conflicts. It is possible that we are troubled as a result of damage in a foreign country which has a close relationship with us. To avoid the worst result, it is preferable to make strong alliances and prepare many choices as resolution. I support the statement of the cabinet.
By the way, Japan will never cause a war intentionally. In the modern era, it is no use for developed countries to begin a war . It will call serious criticism from other countries and sanctions. Japan has so little natural resource that it will not able to continue a war for a long time without being supported by foreign countries. The only risk about it is emotional misconduct of the leaders. We have to keep an eye to them as an ethical and rational citizen.