If the military proclaimed these drones safe and are not shooting them down like crazy, these drones are likely reasonably safe, and are not an enemy that the US military, arguably the top one in the world, would fight.

A possible bad explanation: the US military actually would love to shoot down these drones, but cannot, because e.g. they are known to contain smallpox virus, dangerous radioactive contaminants, etc. These would be released at the slightest attempt to sound alarms or interfere. Someone caught them unawares and is now enjoying impunity.

A worse version: the US military and/or government is complicit, actually overrun by aliens / reptiloids / crackpots, and is allowing an invasion.

Etc.

Which version looks more plausible, any of these, or that the US military is testing something that can fly, but keeps the lips tight?