Photo taken on April 11, 2017 shows military vehicles during the U.S.-South Korea joint Exercise Operation Pacific Reach in Pohang, South Korea. (Xinhua/Lee Sang-ho)

PYONGYANG, April 30 -- The Democratic People's Republic of Korea (DPRK) said on Sunday that the U.S.-South Korea joint exercises and U.S. buildup of nuclear assets on the Korean Peninsula are the root cause of high tension here.

Explaining the situation on the Korean Peninsula to Russian ambassador Alexander Matsegora, DPRK Vice Minister of Foreign Affairs Han Song Ryol said the DPRK will "steadily take measures to bolster up its nuclear deterrence in order to defend the sovereignty and vital rights of the country and peace on the peninsula from the U.S. nuclear war threat."

The Russian side expressed its understanding of the stand of the DPRK and hoped the tension on the Korean Peninsula would be defused as soon as possible, according to the official Korean Central News Agency.

Tension has remained very high over the past two months between the United States and the DPRK over the former's threat to stage military attack upon Pyongyang for its nuclear and missile programs.

The United States and South Korea also held their largest ever joint military exercises in the past two months, while the USS Carl Vinson nuclear aircraft carrier task group has arrived in the waters off the peninsula for joint drills with the South Korean military.