More of a "what if?" documentary philosophising about the invasion of the USA by a ruthless, well equipped, strategically savvy "Enemy" than an action feature. It might be the Russians, or the Nazis - it certainly isn't from outer space... I'd reckon half of it is made up of stock footage; not in itself a bad thing as you can rarely find more authentic ways to reflect warfare (especially aerial) but the use of that footage doesn't stand up to too much scrutiny - last time I looked, the blitz happened in London not New York! There's still plenty of gung-ho dialogue and with the jingoistic presidential addresses, rally crying and reportage you still believe that the invasion could be defeated... It's not dreadful, nor entirely a piece of anti-Soviet propaganda, but the acting is incidental and the intended message clear - "America, be prepared..."