TOKYO, June 20 -- Japan's minimum voting age was officially lowered to 18 from 20 as a revised national referendum law took effect on Friday, in a effort by Prime Minister Shinzo Abe to amend the country's war-renouncing pacifist constitution.

According to Japanese law, a revision of the constitution needs to be initiated with the support of at least two-thirds of the lawmakers in both houses of parliament and must be endorsed by a majority of voters in a referendum.

The revised national referendum law, enacted on June 13, will enlarge the voting population and therefore dilutes the number of those who opposes revision of the constitution's Article 9 which formed the nature of the country's war-renouncing supreme law.

Abe spared no efforts to make Japan a "normal country" and enable it to exercise the rights to collective self-defense, which will allow Japan's Self-Defense Forces to engage war outside Japan, but the collective defense violated the spirit of the country's pacifist constitution.

Currently, Abe's administration seeks to reinterpret the constitution to exercise the collective defense rights in the short term, but in a long run seeks to revise the constitution and the revised national referendum law is a critical step toward the long-term goal.

Nevertheless, amending the pacifist constitution, which has never been revised since its promulgation in 1946, has drawn criticism both domestically and abroad.

Abe's efforts to lift the ban on exercising collective self- defense right by reinterpreting the constitution and expanding arms exports have raised concerns of neighboring countries such as China and South Korea, which suffered from Japan's wartime aggression.