The war-renouncing clause to the Constitution is a threat to national security that leaves Japan vulnerable to foreign invasion and cyber-attacks and should be revised as soon as possible, a conservative citizens' group said Wednesday.

Article 9 is flawed because it prevents Japan from fighting back unless it is under direct attack from an enemy force, journalist Yoshiko Sakurai, the leader of Minkan Kenpo Rincho, said at a news conference in Chiyoda Ward, Tokyo.

The group, whose name means citizens' constitution policy group, has about 180 members, including academics, journalists and business leaders.