Russia called for North Korea to return to the Nuclear Nonproliferation Treaty and agree to new international talks on its nuclear program. President Vladimir Putin also criticized the test.

Russia's Foreign Ministry says the international community should take a measured response to North Korea's announced nuclear test.

In a press statement, the ministry says the North Korean action threatens the peace, safety and stability of the region. It also calls for Pyongyang to return to the Nuclear Nonproliferation Treaty and agree to new talks.

North Korea was a signatory of the treaty, but withdrew from it in 2003. Pyongyang also pulled out of six-party negotiations about its nuclear program last year, talks that included Russia.

Along with China, Moscow maintains cordial diplomatic relations with Pyongyang, but Russia has been unable to use its leverage to convince North Korea to change course.

The ministry gave no indication whether Russia might now back sanctions against North Korea because of the test; in the past Moscow has resisted such a move.

Vladimir Putin

But during a Cabinet meeting, President Vladimir Putin indicated he was not happy about what has happened.

Mr. Putin calls the move a bad development for the Korean people, adding that it causes huge damage to efforts aimed at restricting the spread of nuclear weapons.

He spoke just after Defense Minister Sergei Ivanov reported what appeared to be an underground blast was detected in North Korea. Russia estimated the strength of the explosion would be equivalent to between 500 and 15,00 tons of dynamite.

Russia has sensors located in its Far Eastern region close to the border with North Korea.

Pyongyang conducted the test just three days after the U.N. Security Council made a unanimous call for North Korea not to test a nuclear weapon.