Russia and Japan have criticized North Korea's decision to withdraw from the Nuclear Non-Proliferation Treaty. Japanese Prime Minister Junichiro Koizumi is in Moscow meeting with President Vladimir Putin.
The Japanese Prime Minister began his meeting with President Putin after expressing serious concern about North Korea's decision.
In a statement, Mr. Koizumi said the world community must demand that North Korea reverse its decision to withdraw from the treaty, which was announced on Thursday.
The non-proliferation treaty is the main mechanism through which the world seeks to control the spread of nuclear weapons.
North Korea has now become a top priority in talks between Prime Minister Koizumi and President Putin at the Kremlin, which were originally due to focus on economic matters.
The two leaders are in the unique position of both having met with North Korea's reclusive leader Kim Jong-Il in the past few months.
Along with China, Russia is seen as having a unique position of influence because it maintains good relations with Pyongyang.
Withdrawing from the treaty is the latest move by North Korea in its high stakes nuclear brinkmanship with the United States.
Pyongyang restarted its nuclear program last month after it accused the United States of backing out of a 1994 agreement which ended an earlier stand off.
Washington, in turn, toughened its stand against North Korea in October after the government admitted it was trying to develop nuclear weapons.
In recent weeks South Korea has led an intense diplomatic drive seeking to convince the North to halt its nuclear program in return for security guarantees and new supplies of fuel oil.
