original_query: What actions did the U.S. government take in response to the kidnapping of a civilian prisoner by the Viet Cong?
query: What actions did the U.S. government take in response to the kidnapping of Gustav Hertz by the Viet Cong?
answer: Initial responses were delayed due to the Lunar New Year truce and disbelief that a civilian had been kidnapped.  Later,  attempts included an investigation (spurred by McGeorge Bundy's visit),  negotiations (including a failed prisoner exchange proposed by Robert F. Kennedy), and the rejection of a prisoner swap proposal.  Ultimately, all attempts at securing Hertz's release failed.