China and Russia last week signed a huge, long-awaited agreement on natural gas sales. The $400 billion deal, the largest in the history of the Russian (and Soviet) gas industry, is being hailed as the cornerstone of a new partnership between Moscow and Beijing, "a watershed event" in the words of Russian President Vladimir Putin.

It has already triggered handwringing about a China-Russia axis that invariably follows every meeting of the two countries' top leadership. The gas agreement is important, but it is not a historical turning point.

Beijing and Moscow have for a decade been discussing, and then negotiating, a deal that would supply Russia's oil and gas reserves to the ever-thirsty Chinese economy. Such an agreement would serve both countries — and the world — well. It would diversify Russian export markets, find customers closer to the huge oil and gas fields in the distant east and provide a source of investment for the infrastructure needed to get those resources out of the ground and to foreign markets. China would have a cleaner source of power, diversify its energy sourcing, and would minimize the vulnerability of its energy supply routes. But final agreement proved difficult, with price apparently the big sticking point.