An earthquake measuring 7.8 on the Richter scale hit Wednesday morning off the Russian Kuril Islands, according to the American Seismological Institute.
The institute said that the epicenter of the earthquake is located at a depth of 59 km from the sea and about 1400 km northeast of the Japanese city of Sapporo.
For its part, the US Tsunami Warning Center said it was still "assessing reality to determine the level of risk." He added, "This earthquake has the potential to generate a devastating tsunami in the Masdar region."
The Kuril is an archipelago of dozens of volcanic islands located between the Sea of Okhotsk and the Pacific Ocean, and the control of four of its islands is contested by Japan and Russia.
The four disputed islands are Habomai, Shikotan, Iturovo, and Kunashiri, located in the southernmost part of the archipelago, and Moscow calls it the "Southern Kuril", while Tokyo calls it "the northern lands."
The conflict over these islands has prevented Russia and Japan from signing a peace agreement that officially ended the state of war between them since World War II, despite the return of diplomatic relations between Tokyo and Moscow in 1956.
Tokyo considers the four islands - which are inhabited by about 20,000 people and annexed by the Soviet Union in 1945 - "an integral part of the territory of Japan."