Threatening Lethal Force
In my opinion, the announcement of a robbery while displaying or pointing a firearm is indeed threatening lethal force. In the Medford NY pharmacy robbery on Father's Day, the gunman elected not to leave witnesses and thus executed four innocents. To my knowledge, a gunman does not have to both display a firearm and state how or when he would use it. He could say, "give me the cash and you don't get hurt." Then, execute me anyway.
We are not obligated to take a robber at his word when he promises non-violence in exchange for cooperation.
Int'l Assoc. of Law Enforcement Firearms Instructors