will be realized he said. china has been pushing that point and tension to historic new highs. in the past week, sending nearly 150 war planes into taiwan's air defense zone forcing taiwan's fighter jets to scramble, missile systems to deploy. >> at some point there is going to be a miscalculation and it would be dangerous for the entire region. >> reporter: u.s. officials say they're concerned by the provocation here and warn china against hostile pressure. >> this is about china increasingly challenging american supremacy in part of the world. >> reporter: officially the u.s. doesn't take sides in the dispute over taiwan but just approved a $750 million arm sale to the island and reports of training, too. with american troops including a special operations unit and u.s. toirns said to be stationed on taiwan for over a year. taiwan is now seen as a central issue for