The remains, in caskets draped with powder-blue United Nations flag, were loaded into black hearses after a ceremony outside the 8th U.S. Army headquarters in Seoul that included a 21-gun salute and "Taps."
The remains were brought overland across the heavily fortified Demilitarized Zone (search) that has divided rival North and South Korea since the end of the 1950-53 conflict. They will be flown to Hawaii for identification.
U.S. and North Korean teams recovered the remains as part of a joint search project that began in 1996 and has so far recovered more than 180 remains thought to be of U.S. soldiers.
"Most important is that we will be taking missing Americans from the Korean War back to American soil so they are no longer lost in the hills in North Korea," said Lt. Col. Jerry O'Hara, a spokesman for the U.S. military's Hawaii-based Joint POW/MIA Accounting Command's Central Identification Laboratory.
The United States was a key member of the United Nations coalition that helped South Korea repel the North Korean invasion that triggered the Korea War. The fighting ended in a cease-fire, not formal peace treaty, meaning that the two sides are technically still at war.
The recovery missions have continued despite heightened tensions between the former adversaries over North Korea's nuclear weapons program. The United States and North Korea have agreed to keep the remains issue separate from the nuclear problem, which is being addressed in six-nation regional talks.
Twelve of Thursday's remains were discovered near North Korea's Chosin Reservoir, where the U.S. Army's 7th Infantry Division fought fierce battles with Chinese forces backing North Korea in November and December 1950.
More than 8,100 U.S. troops remain missing from the Korean War, including 1,100 from the Chosin campaign.
The seven others repatriated were found in Unsan County, north of the capital, Pyongyang. Members of the Army's 1st Cavalry and 25th Infantry divisions fought in Unsan County in November 1950.
This year, team members from the United States and their North Korean counterparts have been scheduled to conduct 30-day searches from April through October.
O'Hara said it could take years to identify the remains brought home Thursday, if they are identified at all. As of the beginning of May, only 14 of the 186 remains retrieved through the joint project had been named.