LONDON — A NATO call to study linking U.S., NATO and Russian missile defenses will face technical and security problems so numerous that some experts say the idea is unlikely to go beyond a limited exchange of early warning data.

The broad concept of joint missile defense between the West and Russia dates back at least a decade but has not progressed beyond the theoretical despite a handful of Russia-NATO command post exercises held in recent years to explore the challenges.

Friday’s proposal by NATO Secretary-General Anders Fogh Rasmussen gives the idea a political boost that may lift it into “the realm of possibility,” said Andrew Nagorski, director of public policy at the East-West Institute.

But making the notion a reality would require resolving a long list of military, diplomatic and technical questions that will likely take years, even in the favorable conditions of a diplomatic thaw between Moscow and the West, analysts say. “We are years away. It’s like a discussion of what we’ll do once we land a man on Mars,” said Jonathan Eyal, a defense expert at London’s Royal United Services Institute.

Michael Elleman, a U.S.-based visiting senior fellow for missile defense at Britain’s International Institute for Strategic Studies, said work on missile cooperation would likely focus on early warning radar information exchange.

“If you want to go beyond that, it gets really tricky,” Elleman said.

Eyal said work could only meaningfully start once Washington had executed a revamped U.S. missile shield system for Europe that would replace the plans that had so alarmed Moscow.

“There isn’t even a consensus in Europe or even in NATO over what that system should be, what technology it would apply and how extensive it would be,” Eyal said. “All you have is a tentative American decision unilaterally taken in the hope that the Europeans will follow. They will, I think, follow, but it’s not obvious. And only when that decision is taken can you talk about plugging the Russians into this.”