In case you were too focused on the blood to notice, aviation experts said Wednesday that the helicopters shown in photographs of the raid that killed Osama bin Laden have never before been seen. They have top-secret stealth modifiers that allowed the Navy SEALs to silently sneak up on the suburban compound where bin Laden had been living. In addition to the noise-reducing modifications, the helicopters had a different look than other military helicopters—sharper angles and flat surfaces more common to stealth jets. A senior Pentagon official said the Defense Department would “absolutely not” comment on the helicopters shown in the photos. The military has been working to improve the Black Hawk helicopter since at least 2004, but evidence of the program has never been found in public.