The psychological effect of the V-2 was considerable, as the V-2, travelling faster than the speed of sound, gave no warning before impact (unlike bombing planes or the V-1 Flying Bomb, which made a characteristic buzzing sound). There was no effective defence and no risk of pilot and crew casualties. An example of the impression it made is in the reaction of American pilot and future nuclear strategist and Congressional aide William Liscum Borden, who in November 1944 while returning from a nighttime mission over Holland saw a V-2 in flight on its way to strike London: "It resembled a meteor, streaming red sparks and whizzing past us as though the aircraft were motionless. I became convinced that it was only a matter of time until rockets would expose the United States to direct, transoceanic attack."