BMD and What to do?

Another successful test for the Navy's Ballistic Missile Defense program out in Pac Fleet.... We are well past MAD [Mutual Assured Destruction] and I feel that the number of unreasoning, nonlogical players in the ballistic missile world [much as we all despised the Soviet Union, they DID reason and did not ever launch ballistic missiles against anything we protected] makes having some sort of ballistic missile shield [namely, a system which actually works] a good, common sense item.

Now that we have dispensed with the obligatory stating of where I stand on the issue, let's consider the possible impact upon the fleet, particularly the number of hulls available for various missions. Ballistic Missile Defense can be seen as a national strategic asset, similar to the concept of the SLBM [Sub-Launched Ballistic Missile].

Here's my chain of reasoning: Nuclear response capability is seen as a strategic asset. Providers of same are tasked with a deterring strike as their overall mission. As an example of this, consider the SSBN, the missile firing submarine which deploys to a given geographical region and drives around that area, silently, waiting.... Waiting for the order to empty it's silos and head for home [if it still exists, but that's another discussion for another day].

Following this reasoning, we get the Aegis Cruiser equipped with the ballistic defense versions of Standard Missile. Does this ship then get assigned to patrol the waters roughly between Alaska and Hawaii, waiting for the instance of some illogical regime to launch ballistic missiles in the direction of the US? [North Korea, for instance.] Let's suppose for a moment that the Navy has two zones to patrol, and two ships for each on a rotational basis, making a total of four ships that are now not available for the Navy to use for all of the other missions the Navy undertakes. The fiscal budget is tightening. Will a Democratic President and Congress pay for the Navy to have four additional ships? That's a lot of money, folks.

What should the Navy do? Downplay the BMD mission, letting it slip to the various air and land-based contenders? Play up the BMD, risking having fewer hulls for everything else that what is optimal? What are your thoughts on this matter?