I'd be interested to know if all FIRs/ATC en-route knew it was unmanned and had authority and procedures in place to allow/authorise such a movement in civil airspace.
I believe, for example, that in most EuropeanFIRs any such UAV is only allowed to fly in sterile airspace. Certainly that is the case in the UK.
UAV operations in the UK FIR are very strict (See particularly section 13.3.2. (c))
UAV operations in the UK FIR