A review of the bilateral security treaty between Japan and the United States may become necessary in light of Japan's growing role in contributing to international security, a senior US defense official said Monday.

Under Secretary of Defense for Policy Douglas Feith made the remark amid arguments over the need to redefine the treaty, given the reported US plan to transfer the US Army First Corps headquarters from the state of Washington to Camp Zama in Kanagawa Prefecture, southwest of Tokyo.

On the need to redefine the treaty, Feith said, "There may be a decision that we want to do something more formal."

"There's an argument that it may be a good thing and there is an argument that it may not be necessary," he said in an interview with local and foreign reporters in Tokyo.

But he did not specify how such a redefinition might be achieved.

The envisaged transfer of the US Army First Corps headquarters raises the question of compliance with the Japan-US security treaty, which limits US forces stationed in Japan "to contributing to the security of Japan and the maintenance of international peace and security in the Far East."

But the US command is actually believed to oversee operations across a broader area, including the Middle East, it is said.

"I think the treaty is a good treaty and provides a reasonable degree of flexibility," Feith said.

He suggested that discussions about redefining the 1960 treaty should go beyond its scope of Japan and the Far East clause and encompass global security issues.

On the US plan to realign its forces around the world, Feith said the goal of Japan and the United States is to work on developing doctrine together and carry out combined operations in the hope of serving the broader purpose of working together effectively with all types of military forces.