The destination airport was Phonesavanh Airport in Xiang Kuang province.
Designation is VLPV
Some information here
Pilot information for Phonesavanh Airport @ OurAirports
I only know what my friend in Laos has told me, they are very short of any comprehensive information, everything is very secretive at an official level as it involved a Lao military aircraft and high level officials including the deputy Prime Minister