Royal Air Force Airbus KC2 Voyager (primary use is refueling fast jets) from Brunei International Airport in Malaysia, headed to the general direction of the Persian Gulf. Will keep eyes on.
It disappeared about a minute after I posted.
However, I Spotted a General Dynamics F-16CJ Fighting Falcon over Saar-Hunsrück Nature Park, Germany.
CHEVY F-16C/D 52nd FW Spangdahlem AB GE
The 52d Fighter Wing (52 FW) is a wing of the United States Air Force stationed at Spangdahlem Air Base, Germany. It flies the F-16CJ fighter aircraft. It was activated in 1948, but derives significant elements of its history from the predecessor Second World War 52d Fighter Group, which is now the 52d Operations Group, subordinate to the wing.
The wing provides United States Air Forces in Europe - Air Forces Africa and/or the NATO Supreme Allied Commander Europe with mission-ready personnel and systems. The assigned F-16 aircraft can be tasked to suppress enemy air defenses, provide close air support, carry out air interdiction, counter-air, strategic attack, and combat search and rescue. The wing also supports contingencies and operations other than war as required.
Update: More have appeared! What a show.