Do you really buy that notion? A lot of people on Slashdot were around for the Reagan-Gorbachev talks. Reagan offered to eliminate all nuclear missiles and share a missile defense shield with the Soviets. The two leaders went off on a wild spree of cooperation, leaving their advisors behind, almost agreeing to eliminate all nuclear weapons. They almost had that agreement done at Reykjavík. None of the advisors and tier-two politicians were on board at that point. As soon as they went back to their rooms the walking back began, but a deal was on the table that could have included sharing missile defense research with the Soviets, even though there was nothing that was remotely ready to deploy.
I don't know why that wouldn't count as US policy. The idea was simple..... sign a treaty to eliminate missiles that can reach each other's country. Build a missile defense system that can be used as a backup in case the other side keeps a handful of missiles around. Since you intend to abide by the treaty and eliminate your own missiles, sharing the defensive technology isn't a problem. The thing you gain is a sense of security for both sides.
At the time this was a hugely risky strategy for Reagan, because his defense department believed that the Soviets had a vast superiority in land forces like tanks, etc. Europe would likely have been apoplectic at such a treaty, since the deterrence of US involvement and their huge nuclear arsenal was a great hedge against a Soviet expansion into Europe. Eliminate the missiles and the US couldn't do much to stop the Soviets from taking over more European states - or so the thinking went. I think the conventional wisdom since that time is that the Soviet forces were vastly overrated, and their weaponry was not as formidable as the raw numbers would have indicated. But that doesn't mean it wasn't a bold move.
The Soviets had their own reasons for not wanting to do the deal. But strategically it can only mean that you either don't trust that the US will eliminate their missiles or you are worried that your armies cannot defend your country without your own missiles. (Which is the same position the US was in, they were worried that their conventional forces could not defend against Soviet invasions in Europe)