[krisoft]

> It would be obvious if a strike came from an extraterrestrial source, there would be no terrestrial launch detection.

There would be no launch detected, that is true. That doesn’t mean that it would be obvious that the attack was extraterestrial. The alternative hypothesis would be the that the known terrestrial enemies developed some technique to confuse your sensors, or cloak themselves, or bribe your watchdogs, or pre-position warheads in space, or any other similar deception. People would be sooner thinking that their enemies smuggled nukes in overland than to think that aliens attacked them.