WASHINGTON — Their return home was as elite and secretive as their mission, which ended Saturday in a devastating helicopter crash in eastern Afghanistan.

In a war defined by instant information, cutting-edge technology and a nuanced counterinsurgency, the 30 American service members and eight Afghans killed when an insurgent shot down their Chinook helicopter west of Kabul remained anonymous even as they arrived in the United States Tuesday for the last time.

The fallen service members, most of whom were members of the covert Navy SEALs, carried out some of the most critical missions of the war. Yet it was only in their death that U.S. military commanders disclosed the details of their furtive nighttime operation that ended in the deadliest incident for U.S. forces in the decade-long war in Afghanistan.

On Tuesday, President Obama, Defense Secretary Leon Panetta and top Pentagon officials, along with members of the fallen servicemen’s families, met the men’s remains at Dover Air Force Base in Delaware. Thirty-eight cases – 30 draped with American flags and eight with Afghan flags, for Afghan special forces and a civilian translator – were unloaded from two C-17 aircraft.

Obama had been scheduled to announce new fuel standards for trucks at an event in Virginia but scrapped those plans to travel by plane to Dover. A somber ceremony lasted about four hours, and Obama met privately with family members for 70 minutes. He made no public statements.

Even in death, the service members’ identities retained some mystery.

The Pentagon barred reporters from covering the ceremony, saying that it couldn’t ask families if they wanted media coverage because the remains were unidentifiable. U.S. military officials said Monday that a rocket-propelled grenade struck the middle of the Chinook, effectively splitting it in two as it was landing near a firefight between U.S. Special Forces and Taliban insurgents.

Military officials also declined to release their names, as they usually do for those arriving at Dover, even though more than 20 families already had independently identified a loved one among the fallen.

Nearly every day, Dover receives the body of a fallen soldier from Iraq or Afghanistan, and about 70 percent of the time families agree to allow media coverage.

Those among Tuesday’s cases who are identified through DNA as one of the eight Afghans – including Afghan special forces and one civilian translator – will be flown back to Kabul, officials said. The Pentagon also announced that Army Brig. Gen. Jeffrey Colt would lead an investigation into the crash.