The Cosmic Looters

Wyatt knew his situation was desperate: he couldn't stop the alien invasion, and even if he warned Earth—nobody would believe him!
Duncan Wyatt sprang up, grabbed his gun and started toward the door before he had his eyes properly open. His ears were ringing with the explosive roar that had awakened him and the pre-fab shack still quivered in the shock wave.
He thought the Third World War had started.
He crouched in the doorway and peered out onto the mesa. The unorthodox shape of the experimental ultra-tight-beam transmitter loomed over him, black against the star-blazing New Mexican sky, bearing a red star of its own to warn low-flying planes. He was all alone here. His partner, Bannister, had flown out to the Coast to oversee the making of new components for a projected improvement in design. Wyatt had never felt lonely before, even in the total solitude of the mesa top with nothing around it but the vast impersonals of sky and desert, sun and wind. Now he did feel lonely, and scared. He wondered where the bomb had dropped.
He couldn't see anything, so he went out and around the corner of the shack, keeping low and sticking tight to the wall.
Now he could see a larger area of the mesa, softly but almost adequately lighted by the billion stars above the crystal-clear air.
He saw what it was that had fallen out of the sky.
It wasn't a bomb. It was a—plane? Call it a plane. Call it a rotary-thrust flying wing. Call it anything you want to, it was there, round and glimmering faintly against the drab rock. The boom and shock that had shaken him out of his bunk must have been the result of the thing pulling out of a steep dive at super-sonic speed.
He should have been relieved that this was so. Somehow Wyatt was not. He had a feeling. It was such a crazy feeling that he could not believe it, but he couldn't get rid of it either.
He stood still in the shadow by the corner of the shack and waited to see what would happen next.