There's no proof that the US soldiers were executed.
Yeah, your right...must be a coincedence that they ALL were shot in the forehead.

Iraqi soldiers must be incredibly accurate with their weapons!

besides article 13 of the geneva convention states specifically.
prisoners of war must at all times be protected, particularly against acts of violence or intimidation and against insults and public curiosity.
This means they shouldn't have been paraded and interviewed (interrogated) in front of a camera, for propoganda purposes, nor showing the bodies of dead (executed) soldiers.

They did state that if a camera man is on the battlefield and films (as it is happening) a group of soldiers surrendering, this is not a violation of the geneva convention.