A unit of the U.S. Department of Defense has been holding so-called arrival ceremonies" for seven years, with an honor guard carrying flag-draped coffins off of a cargo plane as though they held the remains of missing American service men and women returning that day from old battlefields. After NBC News raised questions about the arrival ceremonies, the Pentagon acknowledged Wednesday that no honored dead were in fact arriving, and that the planes used in the ceremonies often couldn't even fly but were towed into position. The ceremonies have been attended by veterans and families of MIAs, led to believe that they were witnessing the return of Americans killed in World War II, Vietnam and Korea. The ceremonies also have been known, at least among some of the military and civilian staff here, as The Big Lie. Photos behind the scenes show that the flag-draped boxes had not just arrived on military planes. The Pentagon insisted that the flag-draped cases do contain human remains recently recovered, just not ones that arrived that day. The Pentagon statement did not explain why the rituals were called "arrival ceremonies" if no one was arriving, or why the public had been told that remains removed that morning from the lab were about to go to the lab to "begin the identification process."