Well yeah, remember that whole war montage at the beginning--also known as the only cool bit in that movie? IIRC it went: American Revolution > American Civil War > WWI trenches > WWII Normandy landings > Vietnam.
Of course that raises a whole bunch of other questions, like how does someone in Operation Overlord end up as a POW on Japanese soil? Wasn't he and his half-brother supposedly inseparable during this period? And my personal favourite: isn't Wolverine supposed to be Canadian?