Japan's Self-Defense Forces and the US and Australian militaries have held an opening ceremony for their first trilateral command post drill. The exercise aims to boost their preparedness for the defense of Japan.

The Ground Self-Defense Force and the US Army have been holding a joint command post exercise called Yama Sakura twice a year since 1982. The Australian military is taking part for the first time.

The ceremony took place at the GSDF's Camp Asaka on Monday.

The GSDF's Ground Component Command Commanding General, Takemoto Ryoji, said he believes the exercise will show the deep bond among the three nations and help stabilize a free and open Indo-Pacific.

The commanding general of the US Army's First Corps, Xavier Brunson, expressed hope that Japan and the United States will improve their ability to work together through the exercise. He also thanked the Australian military for its participation.

Officers say participants will confirm procedures for sending troops to Japan from the United States and Australia if Japan is attacked and working with SDF personnel to defend the county. They say Australia's troops will work under the command of US forces.

The exercise is set to last until Wednesday next week.

In June, the three countries' defense chiefs agreed to expand joint drills, with an eye on China's increasing maritime activities.