The emblem of the 357th Armored Huntsman Regiment, 3rd company, 2nd platoon.
Bryan Krueger pointed out to me that the insignia is actually the Finnish air force's blue swastika (Hakaristi) with the gaps filled in (makes sense considering that the other Jerry marking was also Finnish in origin). Interestingly the Finnish Hakaristi predates the Nazi Hakenkreuz (Hook Cross), the symbol apparently being a popular good luck talisman for many pilots during the early years of aviation.
Finland became independent after the break-up of the Russian Empire. Blue and white had always been the Finns' national colours so they were chosen for the national flag and the air force's insignia. Count von Rosen of Sweden was very involved with the setting up of the first Finnish Air Force so his personal swastika emblem was used as a wing and fuselage marking in blue on a white disc. This was sometimes painted on the rudder.
"Von Rosen had painted his personal good luck charm on the Thulin Typ D aircraft. This charm – a blue swastika, the ancient symbol of good luck – was adopted as the insignia of the Finnish Air Force. The white circular background was created when the Finns tried to paint over the advertisement from the Thulin air academy. The swastika was officially taken into use after an order by Mannerheim on 18 March 1918. The FAF had to change the insignia after 1945, due to an Allied Control Commission decree, where the swastika had to be abandoned due to the association with the nazism."
The forces of the U.S.S.R. invaded Finland in 1939. With the German invasion of Russia in 1941, Finland threw in her lot with Germany. The country was forced to sign a peace treaty with the U.S.S.R. in 1944 and to declare war on Germany. A swastika marking was obviously inappropriate, so a white, blue, white roundel was adopted.
The swastika (from Sanskrit svástika) is an equilateral cross with its arms bent at right angles, in either right-facing (卐) form or its mirrored left-facing (卍) form. Archaeological evidence of swastika-shaped ornaments dates from the Neolithic period and was first found in the Indus Valley Civilization of the Indian Subcontinent. It occurs today in the modern day culture of India, sometimes as a geometrical motif and sometimes as a religious symbol; it remains widely used in Eastern and Dharmic religions such as Hinduism, Buddhism and Jainism.
In the Western world, the symbol experienced a resurgence following the archaeological work in the late 19th century of Heinrich Schliemann, who discovered the symbol in the site of ancient Troy and associated it with the ancient migrations of Proto-Indo-Europeans. He connected it with similar shapes found on ancient pots in Germany, and theorized that the swastika was a "significant religious symbol of our remote ancestors", linking Germanic, Greek and Indo-Iranian cultures. By the early 20th century, it was used worldwide and was regarded as a symbol of good luck and success as evident in the above 1920's American postcard. Despite this usage, the symbol has become stigmatized and to some extent taboo in the Western world because of its iconic co-option by Nazi Germany.