SEOUL, South Korea (AP) – The United States will not investigate "every firefight, every battle" of the 1950-53 Korean War, despite allegations that U.S. forces killed unarmed civilians in dozens of incidents, the head of the U.S. Army said Sunday. 

    U.S. investigators are already devoting extraordinary resources to the allegations of a mass killing of several hundred refugees by U.S. soldiers at Nogun-ri, South Korea, in the early weeks of the conflict, Army Secretary Louis Caldera said. 

    Since those allegations became public, South Koreans have come forward with more stories of alleged mass killings of civilians by U.S. troops.  In an interview with The Associated Press, Caldera said it is not possible to investigate every incident of the war in detail.  He said all loss of life was regrettable, but emphasized the need to establish whether civilians were killed intentionally.  "The question is not one of going back to try to identify every incident in which someone claims there was a loss of innocent lives," he said.  "If you begin down that path, you’ll never end because all war by definition is extremely violent." 

    "It is not possible to go back and investigate every firefight, every battle, that occurred during the three years of the Korean War," Caldera said, citing the cruel and chaotic nature of war. 

    The United States and South Korea began investigating what happened at Nogun-ri after The Associated Press reported on the incident in September, citing South Korean victims, American war veterans and U.S. government archives. 

    Since then, 37 other cases of alleged killings have surfaced.  Some South Koreans have said U.S. jets strafed war refugees flooding South Korea’s roads in 1950-51, and there are demands for compensation. 

    Caldera arrived in Seoul on Sunday with a delegation of 18 Army investigators and civilian advisors.  He said his team was making "very good progress" in reviewing U.S. government archives, but he said they had not found anything "conclusive."  He said the compensation issue will be assessed once the investigation is complete. 

    In the AP report, witnesses said a U.S. Army unit killed a large number of civilians in and near a Nogun-ri railroad bridge in late July 1950 as retreating Americans struggled to defend South Korea against a communist North Korean invasion. 

    According to declassified documents, U.S. commanders ordered some units to attack people in civilian garb out of fear that enemy soldiers were infiltrating South Korean refugee columns.  Military law experts say such orders were illegal.