There are a number of potentially hostile countries that could easily strike DC with sea-launched cruise missiles. Our existing radars and satellites have limited to no capability to detect them.
I keep forgetting we're not supposed to care about National Security on FR, though, anymore.
After all the lies told by the fine folks in DC, excuse my cynicism.
Cruise missile #1 ---->>>> Slow, giant target blimp (like shooting fish in a barrel)
Cruise missile #2-n ---->>>> Whatever it damn well pleases