Scandinavian "ghost rockets".

The Scandinavian 'ghost rockets' were roughly 2,000 reports of fast rocket- or missile-like objects seen mostly over Sweden (and Finland) during mid-to-late 1946. Swedish military investigated intensively, suspecting captured German V-weapons being tested by the Soviets from Peenemunde, though most sightings went unexplained and no wreckage was conclusively recovered. They matter as a major pre-Roswell anomalous-aerial wave and an early Cold War intelligence concern that helped frame later UFO investigations.