Foreign Minister Yoshimasa Hayashi voiced "serious concerns" over a recent increase in military activity by Russia and China near Japan in phone talks Thursday with Russian counterpart Sergey Lavrov, a government source said.
The remarks came after Moscow and Beijing sent a flotilla of naval vessels around Japan and conducted a joint bomber patrol over nearby waters in recent weeks in an apparent show of force against Tokyo.
According to the Japanese Foreign Ministry, Hayashi and Lavrov agreed to advance peace treaty negotiations that have been stalled over a long-standing territorial row between their countries.