Russian President Dmitri Medvedev traveled to Paris last week for a three-day visit and to launch a new strategic partnership with France. The new Franco-Russian embrace is marked by major arms sales, a space deal, lucrative energy contracts, and greater market access -- all under the banner of a blossoming personal relationship between Mr. Medvedev and French President Nicolas Sarkozy. But this rapprochement comes at the price of European security.

Talk about history repeating itself. The historical connection between France and Russia dates back to before World War I, when both countries consummated an alliance in 1894. This was a military pact, based on mutual protection guarantees, that cleared the way for massive French loans and weapons sales to Russia -- much as we're seeing today, more than a century later.

For France, the treaty was a way to end its isolation after the ignominy of the 1870 Franco-Prussian war, and the success of Bismarck's policies. For Russia, the reinvigoration of the Triple Alliance (Germany, Austria and Italy) motivated the Romanov dynasty to seek allies further west.

The Franco-Russian amity was also an attempt to keep Germany in check. The arrangement remained in place until 1917 and ultimately fell when the czarist monarchy collapsed. While Nicholas II and the provisional government that followed his abdication were committed to upholding the alliance, the Bolsheviks were supported by the German Imperial General Staff. After Russia's October coup, Moscow and Berlin negotiated the Treaty of Brest-Litovsk in early 1918, ending the Franco-Russian entente.

It was resurrected in 1935, when France and the Soviet Union signed the Franco-Soviet Treaty of Mutual Assistance, which was intended to keep Nazi Germany in check after Germany declared its rearmament. That deal later unraveled when Britain and France agreed to sacrifice Czechoslovakia to Hitler in the 1938 Munich agreement. Stalin decided that France was an unreliable ally, and that a deal with Hitler may encourage the Nazies to fight and destroy Western democracies. So, once Stalin fired his anti-Nazi Foreign Minister, Maxim Litvinov, and signed the Molotov-Ribbentrop Pact, the Russian dictator had committed the Franco-Soviet alliance to the dustbin of history.

Today, once again, Germany figures squarely in Paris's ties with Moscow -- namely, the French desire to catch up to Berlin's current closeness with the eastern giant. Less important factors, it seems, are other NATO members' objections to such links, and Russia's continued violation of the August 2008 ceasefire agreement in Georgia -- brokered by none other than Mr. Sarkozy.

And so Paris moves ahead with the sale of four Mistral-class assault ships to Russia. The Mistral is one of the world's most advanced helicopter carriers, and would be a formidable power-projection tool for Moscow. Building two Mistrals under license in Russia will also boost the Russian industrial capabilities -- a dynamic that should concern the U.S. as well as Europe.

In addition to arms sales, Messrs. Medvedev and Sarkozy last week presided over the signing of an important accord between Gaz de France (GDF) Suez and Gazprom. The deal means GDF will acquire a 9% stake in the Nord Stream gas pipeline, and in exchange, Gazprom will provide France with up to an additional 1.5 billion cubic meters of gas annually from 2015. This follows a close pattern in Russia's diplomatic playbook: Moscow grants selective access to Russian energy resources as a reward for political cooperation -- often in the form of international lobbying on behalf of the Kremlin.

The two countries are also venturing together into outer space, with France set to spend about $1 billion to buy 14 Soyuz carrier rockets from Russia. That agreement builds on an earlier one, which in 2008 locked French satellite launch firm Arianespace into firing off 10 Russian Soyuz-ST rockets.

In France, the motive boils down to a fear of being left behind, and envy of Berlin's special relationship with Moscow, which provides German businesses with billions in profits and with privileged access to Russian natural resources -- one example being E.ON Ruhrgas's lucrative relationship with Gazprom. Even Italy has beaten France to the trough of mega energy deals in Russia, with Rome-based Eni also a principle partner of Gazprom, in the South Stream gas pipeline and other ventures.

In Russia, the new closeness likely has a more internal political angle. It's entirely possible that Mr. Medvedev is jealous of his mentor and former boss, Russian Premier Vladimir Putin, who has formed strong ties with Italian Premier Silvio Berlusconi, and was close to German Chancellor Gerhard Schröder and French President Jacques Chirac when they were in office. Until now, personal relationships and lucrative business deals were reserved for Mr. Putin. The trajectory of Mssrs. Medvedev's and Sarkozy's friendship appears to be a new dynamic, which signals the former's "coming of age."

One can only hope that Mr. Sarkozy will use his apparent leverage to get Moscow on board with tough sanctions on Iran, to counter the dismemberment of Georgia, and to promote Russian rule of law. Paris would also be wise to remember that its gains from Franco-Russian business ties should not come at the expense of European security. That includes the security of France's newest EU brethren, the formerly communist democracies in the East whose adoption of Western ways continues to rankle Moscow. But judging from Paris's warm embrace of Moscow, the future of Russia's expanded clout in Europe has never looked better.

Mr. Cohen is a senior research fellow in Russian and Eurasian Studies and International Energy Policy at the Heritage Foundation. Mr. Graham is a research assistant at the Katherine and Shelby Cullom Davis Institute for International Policy at the Heritage Foundation (www.heritage.org).