I have to wonder, if the ultraterrestrials are brazen enough to do these drones swarms over sensitive military bases - and I presume it's for the purpose of sending a message - why won't they be brazen enough to insert themselves into actual war actions such as what presumably happened with Alexander the Great:
One could suppose they don't want a quick win - drag it out to increase death and suffering to the max not only in the area of battle, but via those effects to the rest of civilization. As it's likely that both the ultraterrestrials and earthly bad guys have directed energy weapons, they could set fire to everything in sight. I haven't decided which provides the most preferred loosh - burning victims alive, torturing them to death, or classic starvation. If the STS team is getting desperate, why not just incorporate their space age tech to get the job done asap? The already recognized grip on mass media would prevent the realization that "aliens" were responsible for the annihilation. Unless, that would be the prelude to introducing them as saviors to the world - they wiped out the middle east "terrorists." War on Terror now officially over.
Of course, we know the wishful thinking factor is going to throw a big wrench in there somewhere, somehow. How bad will things get before the tide turns . . .