tonight, the u.s. military is offering new details on the ambush in niger that left four american soldiers dead. know many basic questions remain unanswered. >> u.s. forces accompanied that niger unit on a reconnaissance mission to gather information. assessment by our leaders on the ground at that time was that contact with the enemy was unlikely. mid-morning on october 4th, the patrol began to take fire as they were returning to their operating base. >> reporter: according to general dunford, troops first requested air support a full hour after initial contact with the enemy. approximately 50 isis-affiliated fighters. >> my judgment would be that that unit thought they could handle the situation without additional support and so what we'll find out in the investigation exactly why it took an hour for them to call. >> reporter: a u.s. drone already in the air reached their position within minutes. french mirage jets responded next arriving about two hours after initial contact.