The sale of the Mistral assault ship to Moscow imperils the security of NATO members and aspirants.

French President Nicolas Sarkozy last week approved the first sale of a Mistral-class assault ship to a foreign nation—Russia. Paris is also considering Moscow's request for three more of these powerful vessels to be built under license in Russia. It's the Kremlin's first major warship purchase from the West since before World War I and the first major weapons sale to Russia by a NATO member.

And what's Alliance's reaction? A big yawn. Secretary-General Anders Fogh Rasmussen announced through a spokesman that NATO doesn't consider Russia a threat. The Baltic nations and Georgia beg to differ. As Russia is not yet a trusted partner, the sale imperils the security of the NATO members and aspirants.

At 23,700 tons and 210 meters long, the ship will be smaller only than aircraft carriers. Capable of transporting up to two landing barges, 30 helicopters, 900 commandos, 13 tanks and numerous armored vehicles, the Mistral will be a formidable power projection tool. It is already making governments around the Black and Baltic Sea littorals shudder. Russian ship-based attack helicopters are particularly important for naval reach and punch.

There is even a talk of deploying a Mistral with a reinforced hull to the Arctic as competition for natural resources there heats up. Vladimir Putin has made it no secret that he would deploy the Mistral-class ships wherever he wants. And these vessels have great command-and-control, communications and intelligence capabilities.

Turning away from the Soviet-era autarchy, Moscow is planning to buy sophisticated armaments from abroad—Mistrals from France or, as recently reported, advanced unmanned aerial vehicles from Israel. The plan is to then either reverse-engineer the new weapons or produce them under license to force-march its obsolescent military to the 21st century.

Russia's naval modernization should particularly worry NATO. Since the 18th century, Russia has traditionally built up its smaller sea fleets in the Baltic and the Black Sea before "upgrading" to a blue water navy. Building a modern navy will intimidate Russia's neighbors and open doors for Russian power projection in the Mediterranean and the Middle East.

France's decision to go ahead with the deal without prompting any NATO objections is particularly disturbing in light of Moscow's recent aggressions. It's just some 18 months ago that the Russians snubbed Mr. Sarkozy when they refused to comply with the French-brokered Georgia War cease-fire agreement President Dmitry Medvedev had signed. Then last fall Russia conducted a military exercise in which Moscow simulated a nuclear attack against Poland. Once again, NATO didn't protest. And last year Russia changed its laws empowering the president to deploy troops abroad without any parliamentary approval. Finally, President Medvedev two weeks ago signed a new military doctrine that declares NATO a threat and calls for the protection of vaguely defined "compatriots" and lowers the threshold for pre-emptive nuclear strikes.

Europe greeted all these destabilizing policies by queuing to buy Russian natural gas, feting Mr. Putin in Paris and Berlin, and selling him modern weaponry. Lenin called this "capitalists selling us the rope with which we will hang them." Only this time, Russia may try to hang Ukrainians and Georgians first, before expanding its naval might to the Mediterranean, the Baltic and the North Atlantic.

Given that the vital supply route to Afghanistan passes through Russia and its allies in Central Asia, it is perhaps understandable that NATO is still trying to build bridges with Moscow. The Obama administration also keeps pushing the "reset" button with the Kremlin, hoping Moscow will finally help stopping Iran's nuclear weapons program and complete the negotiations on strategic arms reduction. Washington also kept mum about the Mistral deal so not to antagonize the Elysée, in the hope that President Sarkozy might still send more French troops to Afghanistan—which he didn't. Nor does President Barack Obama want to endanger Paris' crucial cooperation on Iran.

Still, the Mistral security threat is significant. Things may change in the future, but today selling these warships sends the wrong signal to NATO members, to aspirants, as well as to the Russians. At a time when Moscow still views NATO as an adversary, abandons the Conventional Forces in Europe Treaty, which limits heavy arms deployed West of the Urals, and occupies 20% of Georgian territory, a major weapons sale to Russia is premature. This is especially true when the sale is a part of a major naval modernization program that may jeopardize the Alliance's flanks and important energy routes.

NATO members may want to wait on expanding their military cooperation with Russia until Moscow fulfills the August 2008 Medvedev-Sarkozy cease-fire agreement and restores its credibility with the West.