A special Japanese police squad trained and equipped to respond to hostage-taking and other incidents has its origins in the aftermath of terrorist attacks in the 1970s and 1980s by the now-disbanded Japanese Red Army.

The former leader of the militant group, Shigenobu Fusako, was released from prison on Saturday. In 1977, the group hijacked a passenger plane and forced it to land in Dhaka, Bangladesh, and demanded the release of group members from prison.

At the time, the Japanese police had no system to respond to such terrorist attacks.

The government decided to accept the group's demands as extralegal measures, and released six detainees. They also paid 6 million dollars in ransom.

Following the incident, the Japanese police authorities established the Special Assault Team, or SAT.

SAT members are trained with special equipment such as rifles and stun grenades. They can be mobilized to respond to hostage-taking and other incidents across Japan.

A series of hijackings also caused Japanese authorities to step up security screening of passengers at airports before boarding, and to join counterterrorism measures in cooperation with other countries.