Liberal Democratic Party Secretary-General Shigeru Ishiba proposed Wednesday that Japan might consider finding other collective self-defense partners in addition to the United States, its closest security ally.

"We must discuss whether the United States should be the sole option or if the scope should be widened to include many other countries," Ishiba, the No. 2 man in the party, told an event in Washington.

"Some say the possibility should be limited to the United States," Ishiba told a symposium hosted by the Sasakawa Peace Foundation.