The Vietnamese slowly began to return American remains that they had previously collected and stored ; eventually they permitted the U.S. to excavate a few crash sites .
The U.S. government viewed this work as a humanitarian obligation .
The Vietnamese slowly began to return U.S. remains that U.S. had previously collected and stored ; eventually U.S. permitted the U.S. to excavate a few crash sites .
The U.S. government viewed this work as a humanitarian obligation .