An article in The Wall Street Journal describes "How We Bury the War Dead" from our earliest wars up to today, including the eventual decision to bring all the bodies home:
.... The modern system for cataloguing and burying military dead effectively began during the Civil War, when the enormity of the carnage triggered a wholesale revolution in how the U.S. treated fallen troops. Congress decided that the defenders of the Union were worthy of special burial sites for their sacrifices, and set up a program of national cemeteries.How We Bury the War Dead - WSJ.com
During the war, more than 300,000 dead Union soldiers were buried in small cemeteries scattered across broad swaths of the U.S. When the fighting stopped, military authorities launched an ambitious effort to collect the remains and rebury them in the handful of national cemeteries. ....
The first time the U.S. made a serious effort to repatriate the remains of soldiers killed overseas came during the Spanish American War of 1898, when the military brought back the remains of thousands of troops who were killed in places like the Philippines and Cuba.
The relatives of fallen troops in both world wars were given the choice of having their loved ones permanently interred in large overseas cemeteries or brought back to the U.S. for reburial. ....
Today, the remains of 124,909 fallen American troops from conflicts dating back to the Mexican-American war are buried at a network of 24 permanent cemeteries in Europe, Panama, Tunisia, the Philippines and Mexico.
The military reshaped its procedures for handling war dead during the Korean War, when territory changed hands so many times that temporary U.S. battlefield cemeteries were at constant risk of falling into enemy hands. In the winter of 1950, the U.S. launched a policy of "concurrent return," which called for flying the bodies of fallen troops back to the U.S. as quickly as possible. .... [more]