Warfare History Network
With hot air balloons?
It crossed silently on a chilly winter evening over the southern Oregon coast, descending slowly, its ballast spent. The Japanese bomb-laden paper balloon collapsed into the Gearhart Mountain forest near the line separating Lake and Klamath Counties in south-central Oregon. The undercarriage of the 70-foot balloon slammed into the earth, its impact muffled by several inches of snow, which prevented a 33-pound high-explosive...
Read this story at The National Interest