I think that's a policy question.
That said, I think policies related to ballistic missile offence are becoming less and less relevant. Now, our allies have adopted the concept of integrated air and missile defence, which is built on three systems: a sensor system, a threat response system, and a command and control system.
Since all the systems are fully integrated into a single network and since there are multiple threats—ranging from hypersonic threats to various missiles including cruise missiles—it's hard to target just one specific threat. Integrated air and missile defence is the concept of the future.