"if a criminal/terrorist is holed up so that law enforcement lives are endangered to remove them,"
Where is the line? What about civilian lives? Do we have hellfire armed drones circling the city. Track the convenience store robber. Fire a missile at his car as he drives away? Law enforcement lives are endangered by just sitting in their cruisers, who wants to risk a chase? Maybe we should put speed radar on the drones and fire on speeders. Law enforcement is in danger any time they pull someone over.