Japan’s call to maintain “impeccable” defences on its northern frontier reflects Tokyo’s deepening concern over growing Russian military activity in the region, analysts say.

They also point to rapid north-south troop deployment exercises as preparation against a potential “diversionary operation” around Hokkaido: a scenario in which Russia could open a second front if Japan were already focused on a crisis with China in the south.

During a visit to military bases in Hokkaido on Saturday, Defence Minister Shinjiro Koizumi expressed alarm over Russia’s increasing military activities in its Far East region, saying this made strengthening the defence of Japan’s northernmost main island essential.

Russia’s military posture in the Far East region “is a cause for serious concern along with its strategic cooperation with China”, broadcaster NHK quoted Koizumi as saying.

“Even as the importance of strengthening the defence of the southwestern regions grows, Hokkaido remains a vital region, and it is necessary to continue maintaining an impeccable defence system here,” he added.

Koizumi had earlier visited the Self-Defence Force’s Makomanai Garrison in Sapporo and Chitose Air Base, around 40km (25 miles) to the southeast.