You have abstracted things a bit too far.

Unless your interceptor system is unobtainium laser system with unobtainium cooling system, backed-up by unobtainium power source, you are going to run out of interceptor missiles (or even Phalanx bullets) way sooner than 'million missile attempts'.

Quite possibly 100-200 Shaheds + half a dozen proper anti-ship missiles will cause you to turn tail.