You'd be surprised just how many fully operational tanks are in civilian hands.... They are perfectly legal under US law to own and operate.
As for an ICBM, non-nuclear, technically, as long as it's registered with the ATF as an other than explosive device, it's perfectly legal and has been since 1791...(if they'd existed then)
with nukes, you get into mass destruction weapons. Not firearms or arms. Apples and bannas there Timmy