All four candidates in the Liberal Democratic Party's presidential election said Sunday that Japan should be able to exercise the right of collective defense, a controversial issue related to the war-renouncing Constitution.

Under the government's current interpretation of Article 9 of the Constitution, Japan "cannot exercise" the right of collective defense because the article bans the use of force as a means of settling international disputes.

"It would be better to do so in the future," Prime Minister Junichiro Koizumi said during a debate on Fuji TV when asked if the Constitution should be amended so Japan can exercise this right.