@hobs I'm not sure what the plane is, but the Canberra and the U2 were/are both over 70,000 feet cruising altitude. I think one of the big USAF drones can also fly close to that high.
@hobs https://www.militaryfactory.com/aircraft/aircraft-ranked-by-ceiling.php
If the balloon was cruising at FL60, there are a whole bunch of aircraft capable of getting there.