No warhead is wanted or needed. Published estimates of Minuteman accuracy at intercontinental range were about three hundred feet for a pure ballistic flight and no terminal guidance. The GPS satellites fly through the Van Allen Belt and thus are radiation hardened, but they too are vulnerable to other kinds of attack. Without intact space assets much of the US high technology capability vanishes in the first hours of the war. While the energy equivalence of air travel and rocket flight to orbit are not exact, they're close enough for first approximations.
Airlines typically operate at a small multiple of fuel costs.
There is no reason why spacecraft cannot do so as well. See my SSX papers in this series. This Megamission is the easiest to ignore , but you ignore it at your peril. Portions reprinted in articles by the authors and F. X. Kane. This book is now available as shareware on this web site.