"Start! ... The Delta IV Heavy launch vehicle lifts off from Vandenberg Space Center from Launch Complex-6 as part of the NROL-91 mission," the company's Twitter post reads.
According to the data presented on the official ULA website, the launch took place at 01:35 Moscow time.
The rocket is on a mission for the US National Space Intelligence Agency.
Vitaly Kiselyov, Assistant Minister of the Interior of the Lugansk People's Republic, said earlier on Channel One that the intelligence of NATO member countries monitors "almost every centimeter" of Donbass from satellites.
According to a member of the Russian hacker group RaHDIt, US intelligence is supplying Ukraine with radar data and satellite imagery, including Russian territory.