"Stephen Ambrose, in his book D-Day, talks about the Korean men found on Utah Beach. The National Archives caption for this photo says he’s Japanese, but he's not. Well, technically he is Japanese since all Koreans were legally Japanese nationals during WWII.
Here is a quote from the book:
"The so-called Ost (east) battalions became increasingly unreliable after the German defeat at Kursk; they were, therefore, sent to France in exchange for German troops. At the beach called Utah on the day of the invasion, Lt. Robert Brewer of the 506th Parachute Infantry Regiment, 101st Airborne Division, U.S. Army, captured four Asians in Wehrmacht uniforms. No one could speak their language; eventually it was learned that they were Koreans. How on earth did Koreans end up fighting for Hitler to defend France against Americans? It seems they had been conscripted into the Japanese army in 1938 -- Korea was then a Japanese colony -- captured by the Red Army in the border battles with Japan in 1939, forced into the Red Army, captured by the Wehrmacht in December 1941 outside Moscow, forced into the German army, and sent to France. (What happened to them, Lieutenant Brewer never found out, but presumably they were sent back to Korea. If so, they would almost certainly have been conscripted again, either into the South or the North Korean army. It is possible that in 1950 they ended up fighting once again, either against the U.S. Army, or with it, depending on what part of Korea they came from. Such are the vagaries of politics in the twentieth century.) By June 1944, one in six German riflemen in France was from an Ost battalion"
They served in the Ost (German for East) battalions, which were troops captured on the Eastern front and sent to fight in the trenches in Normandy. They were considered unreliable troops since they were not Germans. But under defensive works, with officers who had pistols behind them, they could expect to provide a small measure of resistance. "