Well think about this way. What if one day, a person with powers came and destroyed the country's capital without any warning probably killing hundreds and injuring even more. Then all of a sudden, even more powered beings show up and start brawling it out in the middle of the destroyed capital. Also, don't forget the fact that they already hate them. When they try to come to terms with them, their ambassador literally gets his head chopped off by one of them. Then too make matters worse, a flying ship literally comes out of nowhere carrying even more of these super powered beings. I don't know what military would seize fire at this. In fact, especially from Jack's scale of power, they should've sent a nuke by now.