Japan is facing its most severe security environment since World War II as three potential adversaries in East Asia – China, Russia and North Korea – ramp up military activities in the region, the country’s defense minister said Tuesday.

Russia’s foreign minister warned the United States, South Korea and Japan against forming a security partnership targeting North Korea as he visited his country's ally for talks on further solidifying their booming military and other cooperation.

Russian Foreign Minister Sergey Lavrov traveled to North Korea on Friday to meet with his North Korean leader Kim Jong Un and others during a three-day visit.