I guess "US commercial drones" is the gap or intersection of the relevant Venn diagrams, but that doesn't make sense. Why would you test them over a military base?
I think we can apply some Gaussian blur and assume the statement is an approximate fit to the meaning by remembering that: this was a statement provided by a human in real time, ad libbing in response to a press question. They didn't spend hours drafting it to elucidate all possible logical connections and deftly conceal the unstated meaning by crafting some inference puzzle. Hahaha! :)
Communication between people is successful miscommunication. It's not an API - remember that, engineer! :)
That is different than the statement:
* The Pentagon has stated that (a) X is true, and (b) they have no evidence that Y is true.
* Where X is defined as "These are not US military drones"
* Where Y is defined as "these activities are coming from a foreign entity or the work of an adversary"