Your first option comes with the major caveat that each interceptor you fire comes from a limited stockpile whose replacement rate[0] today isn't sufficient for even going 1:1, let alone accepting that multiple interceptors are required.

I'd say the real options in the near term when faced with an inbound missile is a) deciding to deplete your stockpile of interceptors with an incredibly limited replenishment rate; or b) risking a hit to a lower-value target.

Could the US go to a war economy footing and scale production? _Maybe_? I'm not entirely convinced the US can stomach the costs.

[0]: again, numbers are hard to find, but https://www.lockheedmartin.com/en-us/news/features/2026/Lock... gives a flavor of just what defenders are up against.

In theory; in practice however, there's been rocket fire from Gaza towards Israel where the offence was literally a metallic tube with a bit of TNT at a cost of about $800 per rocket [0] while the defence was $100,000+ per interceptor [1]. This has been going on for years, and as far as I'm aware there was no depletion observed.

[0] https://en.wikipedia.org/wiki/Qassam_rocket [1] https://en.wikipedia.org/wiki/Iron_Dome