Oh yeah, because russia is the only country with nuclear weapons. In fact, russian weapons are so good and fast that they arrive at their destination before they press the launch button. The west can only retaliate by throwing stones at them. Well, that's what you lot would have us believe, anyway.
Un-interceptable missiles are Russia's answer to the US pulling out of the ABM treaty, iirc. They allow Russia to be able to strike back in the event that they are attacked. This ensures mutually assured destruction.
In the event that Trump pulls US support from Ukraine, and Europe went to war with Russia without the US, the first thing Russia would do is destroy our nuclear deterrent. That would probably cause Europe to think again.