Japan's new security laws took effect Tuesday, enabling its troops to fight overseas for the first time since World War II in a landmark defense policy shift in a country with a war-renouncing Constitution.
The reform enacted by the government of Japan's Prime Minister Shinzo Abe is intended to deal with the security environment Japan faces, such as China's military assertiveness and North Korea's nuclear and missile threats. But it remains controversial among the public who fear the laws could erode Japan's postwar pacifism, according to Japan's (Kyodo) News Agency. 
The laws largely expand the role of the Self-Defense Forces overseas. 
The most notable change is that Japan is now allowed, in a limited manner, to exercise the right to collective self-defense or coming to the aid of the United States and other friendly nations under armed attack even if Japan itself is not attacked.

Source: QNA