Japan is particularly concerned with Russian expansionism, because it is the only G-7 country that currently has a territorial dispute with Russia, which has occupied its Northern Territories since the waning days of World War II. That occupation began between August 28 and September 5, 1945, when the Soviet Union hurriedly nullified the existing Soviet-Japanese Neutrality Treaty and invaded not only Japanese-occupied Manchuria, but also southern Sakhalin Island and the ancient Japanese territories of Etorofu Island, Kunashiri Island, Shikotan Island, and the Habomai Islands.