The Soviet Union and the People's Republic of China were unforgiving "enemies" from the mid-1950s through the end of the Cold War. True, the two communist giants did - with great caution - collaborate to arm and train the North Vietnamese during the Vietnam War. But politically and even ideologically they were enemies.

Indeed, after President Richard M. Nixon's visit to China in 1972 the United States and China entered a period of limited cooperation aimed against the Soviet Union. Over the past 35 years this relationship has had up and downs - in the 1980s the Reagan administration began a military relationship, which included the establishment of a U.S. "listening post" in China to intercept Soviet communications; during the Clinton administration there was considerable technology transfer to China, while U.S.-China economic ties grew precipitously.

Following the demise of the Soviet Union at the end of 1991 Russia and China entered a new relationship, which soon included massive sales of Russian military equipment to China including high-performance aircraft, destroyers, submarines, and other advanced weapons. Now Russia and China have reached a new level of cooperation - some might label it collaboration.

Russia's new president, Dmitri Medvedev, has just completed a visit to Beijing. With China's President Hu Jintao, Medvedev has signed a joint statement declaring that Russia and China are ready to push forward a new level of economic cooperation between their nations. Medvedev said that his country's relationship with China is now a driving force on the world stage and can no longer be ignored - that the international community can no longer make major decisions without the participation of the two countries. He added that Russia will continue to pursue close ties with China, even if it makes other countries uneasy. "Our activity is not directed against any other country but serves to maintain an international balance," Medvedev said of Russia's new level of cooperation with China.

Among the other declarations of the two leaders during the May visit by Medvedev, they joined in criticizing plans of the United States to build a missile defense system in central Europe. From the start of that effort the Russian government believed that its purpose was to neutralize Russia's IBCM force.

Both China and Russia are veto-wielding permanent members of the United Nations Security Council, where they have coordinated positions on controversial issues such as independence for Kosovo, which both countries oppose, as well as the Iranian nuclear issue. And, unlike most Western nations, Russia has not voiced concerns about China's human rights record or its assault on the protest movement that erupted against Chinese rule in Tibet last March.

This was Medvedev's first official foreign trip since becoming Russia's president earlier in May. That action in itself is of major international significance. During their May meeting President Hu accepted an invitation from Medvedev to visit Russia in 2009.

The two leaders also signed a $1 billion agreement for Russia to build a uranium enrichment facility in China. Not publicized, their staffs also discussed an increase in military cooperation between the two countries.

Meanwhile, Russian air and ground forces are dispatching planeloads of humanitarian aid to China to help with earthquake relief efforts.

Not yet clear are the long-term implications for the United States and other Western states of the new Russia-China relationship. Prior to the recent meeting in Beijing, alarmists in the United States called attention to Russian military sales to China. These are expected to increase. Less attention has been given to the more important implications of Chinese efforts to increase influence and to obtain critical resources in Africa and the Middle East. Russian-Chinese collaboration could certainly exacerbate this situation.