Egypt launched its military offensive hours later, carrying out missile strikes from helicopters.

BBC: Egypt tribes back offensive against militants in Sinai

It was intended to make possible deep cuts in offensive arms that might otherwise have been needed to overcome missile defenses.

CENTERFORSECURITYPOLICY: Reagan's vision

Ideally, America's defence chiefs would like an unrestricted choice as to what sort of anti-missile defences to deploy, and what size of offensive arsenal to keep.

ECONOMIST: Russia and the United States: Best of foes | The