The Social Democratic Party declared Saturday at its party convention that the existence of the Self-Defense Forces violates the pacifist Constitution, reversing a 12-year-old stance on the legality of the SDF.

"We aim to reduce the scale of the (forces), which are apparently unconstitutional, to reassign them to the duties of border security, disaster relief and international cooperation so we can have an unarmed Japan," the declaration said.

The move is apparently aimed at boosting the SDP's standing as a pacifist party. Once the main opposition party, the SDP has seen its Diet strength dwindle over the years. The SDP currently has only seven seats in the 480-seat House of Representatives and six in the 242-seat House of Councilors.

Prior to 1994, the party stuck to a policy that the existence of the SDF was unconstitutional. This was reversed when SDP leader Tomiichi Murayama became prime minister in an coalition government with the Liberal Democratic Party and the now defunct New Party Sakigake.

On the Japan-U.S. Security Treaty, the SDP said in the declaration that it should be turned into a peace and friendship treaty, while seeking the reduction and termination of U.S. military bases in Japan.

It also said the party wants to achieve the constitutional ideals and correct social disparities, rather than prioritizing profit-seeking and efficiency.