Sort of.
The problem with missiel shields is that it deconstructs MAD - and therefore places the part outside the shield in the position of being vulnerable to a nuclear attack.
The point of nuclear weapons, as I am sure you are aware, was originally to blow your enemy up real good - but over the course of the development of spacecraft and truly intercontinental missiles, the purpose of nuclear weapons became a deterrent against the OTHER guy who had them. The maintenance of a nuclear arsenal is a guarantee the other side will not use theirs, since the inevitable result of first use is a retaliatory strike. This is one of the reasons that arms reduction talks started in the 70s and grew from there; as the purpose of nukes went from being fyour biggest offensive weapon to your way of making sure the other guy didn’t use his, the need for enormous arsenals was lost. Countries started basing their strategies not around having 40,000 nukes so you could use them everywhere, but having the right number of nukes that **your enemy would be assured of his own doom if he forced you to use them. **
One of the unspoken rules of the international balance of power is therefore a recognition that this state exists. But that means that by threatening to stop the other enemy from using HIS nukes, you make it possible for you to use your own.
That’s what Russia sees as being threatening about this - well, no, more precisely, it’s one of two things, the other being the smaller of two warring camps, but that’s another issue. the problem with ABM defense is that it’s a defensive weapon that makes you the potential aggressor. If you have a missle shield, you can use your missiles with impunity.
Imagine if the USA or USSR had suddenly invented and started to deploy, over a six month period, a full blown, 100% reliable missile defense in, oh, 1982. What would the result have been? If it’s the USSR, the USA is now facing the possibility of a Soviet enemy who has no reason NOT to launch a war - you can’t nuke them. And the reserve would also be true; if the USA can raise a shield, they can win World War III in a month.
So what do you do? Why, you just might be inclined to start the war BEFORE the shield is up. You can’t trust your enemy to hold that sword over your head; they may SAY it’s for rogue states but if it works, it gives them the jump on you.
That’s why there was an ABM treaty. If you have a perfect shield, you’ve just more reason to use your spear.