So arguably much closer to dropping infantry, except that you'd have to warn them if you don't want to kill civilians.

Yes, it is.

But it seems to had another use. The W66 warhead has been used in the Sprint anti ballistic missile, to intercept and destroy ICBM.

I've always wondered: reused- by whom? Assuming these things would be droppped during a nuclear war (otherwise, dropping one would start the nuclear war) there wouldn't be many people left to reuse the buildings. Or any other living things for that matter.

>Neutron activation from the explosions could make many building materials in the city radioactive, such as zinc coated steel/galvanized steel (see area denial use below).

After you!

That's not really the intent. Mostly the idea was that the armor on a tank will do a good job protecting from the blast and heat but a poor job protecting against neutrons. So if you want a weapon to attack an column of armor you're better off having your warhead put as much of its energy into neutrons as possible.

Really, bombarding things with neutrons is not what you want to do if you want to re-use something. Some elements become radioactive when they absorb a neutron and if if you want to re-use that infrastructure you'd probably be better off letting it take some blast and then repairing it.