Engine exhaust, no fuel dump.
Uh, sir, the Russians just planted a flag at the other pole.... LOL
LOL!
Based on the trail from the boom, then they are pushing the last bit out of the boom before retraction. I had the opportunity to see an EC-135 land that could not retract the boom. They were near dry anyway but even with that when they finally had to land with the boom extended about 150 feet the flames and smoke coming from the dragging boom were impressive. The pilot had the aircraft at a stop halfway down the runway and the flight crew and ALCC crew gave us all a flawless example of a record time evacuation of an aircraft.