Yes, under most definitions of the term "advisor." On Oct. 18, 1943, Major Gen. John R. Deane arrived in Moscow to open the U.S. Military Mission to the Soviet Union under U.S. Ambassador Averell Harriman.

The United States had been shipping military equipment to the Soviet Union for more than two years by this point, and the Soviet Union even had airmen in the United States, on the ground in Alaska, where they received aircraft and flew them into the Soviet Union. Stalin and the Soviet government were notoriously suspicious of the United States, and the American government went to great lengths to appease the Soviets ─ even going so far as to court-martial airmen who disobeyed Soviet instructions.

Now, the U.S. Military Mission was not a strictly training mission in the sense that you think of it. It was primarily geared toward information-sharing and working out any kinks with Lend Lease.

One of its more significant projects was Operation Frantic or Operation Baseball, a shuttle bombing mission from England to Poltava. The idea was that by flying from England over Nazi Germany and landing in Soviet territory, American bombers could strike targets otherwise unreachable.

Thirteen hundred airmen were assigned to the operation in summer 1944, but four months of operations failed to create success. The Soviets vetoed some targets, German aircraft bombed the Poltava base, logistics were a nightmare and the Soviets threw up political hurdles. The whole operation was quietly dropped by October 1944. A skeleton crew of 300 Americans remained at the base until after the end of the war.