Japan needs to play a greater role in addressing regional crises in the dynamic Asia-Pacific region and secure a position as a "tier-one nation," according to a new report released Wednesday by a group of U.S. defense experts.

"Japan should expand the scope of her responsibilities to include the defense of Japan and defense with the United States in regional contingencies," said the report on the Japan-U.S. alliance published by the Washington-based Center for Strategic and International Studies.

"Japan is at a critical juncture" between complacency and leadership, the report said. "In choosing leadership, Japan can secure her status as a tier-one nation and her necessary role as an equal partner in the alliance," it said.