The Ground Self-Defense Force underwent its biggest organizational shake-up Tuesday, with command streamlined for flexible nationwide operations and the creation of amphibious forces tasked with defending remote islands.

The launch of the Ground Component Command to provide unified command over regional armies and the Amphibious Rapid Deployment Brigade, akin to the U.S. Marines, came as Tokyo seeks to beef up defenses against North Korea's nuclear arms and missile programs and China's maritime assertiveness.

"We are expecting more situations in which the Ground, Maritime and Air Self-Defense Forces have to work together to rapidly respond at a nationwide level against ballistic missile launches, attacks on islands and major disasters," Defense Minister Itsunori Onodera said at a news conference, emphasizing the role of the Ground Component Command in such scenarios.