P brought this action in the United States District Court under the Federal Tort Claims Act, 28 U. S. C. §§ 1346 (b), 2671-2680. P sought recovery for property damage allegedly resulting from a sonic boom caused by United States military planes flying over North Carolina on a training mission. The District Court entered summary judgment for D. The Fourth Circuit reversed. That court held that, although P had been unable to show negligence 'either in the planning or operation of the flight,' they were nonetheless entitled to proceed on a theory of strict or absolute liability for ultrahazardous activities conducted by petitioners in their official capacities. The Supreme Court granted certiorari.