Think logically.
For what reasons would you test air defenses?
What information would you need from said tests?
What resources are required to act on that information?
What is the purpose of that action?
Can China launch a meaningful strategic attack against the U.S.?
What would the U.S. response be?
Can Russia?
What would the particular benefit of those actions be?
Why has the U.S. not blamed Russia? China?
Why, then report that objects yet to be publicly seen have been intercepted?
What model fits the data?