Russia's navy has test-fired two supersonic anti-ship missiles at a mock target in the Sea of Japan, the country's defense ministry says, as tensions continue to escalate in the wake of Tokyo's growing military ties with the US.

North Korea launched at least one long-range ballistic missile into the sea off its east coast, after Pyongyang warned of a strong response to upcoming US-South Korea military drills.

Russian and Chinese air forces have carried out joint military exercises in the Asia-Pacific region, according to Russian defense ministry, demonstrating closer defense ties in the face of increasingly hostile West.

Russia and China have carried out several other drills in recent years.

The US and Japan say they have staged joint fighter jet flight over the Sea of Japan after missile launches by North Korea.

Russia and China has begun joint naval drills in the Sea of Japan.