Nobody saw the Ship by Murray Leinster

It was only a tiny scout ship from somewhere beyond the stars; only one alien creature occupied it. But the ship's mission spelled life to its fellow creatures and death to all living creatures on Earth. And against the super-science of the raider stood one terrified old man and his dog…. The landing of the Qul-En ship, a tiny craft no more than fifteen feet in diameter, went completely unnoticed, as its operator intended. It was armed, of course, but its purpose was not destruction. If this ship, whose entire crew consisted of one individual, were successful in its mission then a great ship would come, wiping out the entire population of cities before anyone suspected the danger. First published 1950 Ovi magazine publishing: May 2023