(CNN) What is a suspected Chinese spy balloon doing above the US?

Refer to CNN Exclusive: FBI investigation determined Chinese-made Huawei equipment could disrupt US nuclear arsenal communications. A possible explanation:

• Inside the skin of the balloon, there is an electronically steerable antenna array.
• A goal is to intercept and precisely determine locations of 44 gHz uplinks (from ground station to satellite) of the Milstar system.
• This knowledge could be used to disable one of the redundant command paths for the nuclear deterrent.
• The uplink beams are very narrow, not practical targets for typical satellites.

The National Reconnaissance Office has space-based ability to do this; the sigint satellites cost $1BN apiece. This is currently beyond the capabilities of China.