I've been flying to and from St. Thomas for more years than I care to admit out of JFK, EWR and PHL. I've never had anything other than a direct flight with no fuel stop required back to the US.
I stand by my comment.
How many years ago did you start flying from STT to the USA nonstop? The current STT airport was constructed with longer runways in 1990. Prior to that it was not possible for jets to fly nonstop without either a fuel stop or reduced load due to the short length of the runway.
According to the 1 Jan 91 Official Airline Guide, the following flights operated from STT to the mainland USA:
American 655 (Airbus A300): STT-STX-JFK (flight's first leg is JFK-STT)
Continental 619 (727-200): STT-STX-EWR
Pan American 222 (727-200): STT-STX-JFK (the flight's first leg was MIA-STT
Midway Airlines 745 (737-200): STT-STX-MIA-MDW (continued to BDL except Saturdays)
Midway Airlines 747 (737-200): STT-STX-MIA-MDW
Pan American 430 (727-200): STT-STX-MIA-DCA
Pan American 221 (727-200): STT-STX-JFK (first leg: MIA-STT)
American 1467 (727-200): STT-STX-MIA-ISP (first two segments: IAD-RDU-STT)
Eastern 996 (727-200; discontinued after 3 Jan 91): STT-STX-MIA
American 1466 (727-200): STT-STX-RDU-IAD (first two segments: ISP-MIA-STT)
Eastern 990 (727-200): STT-STX-ATL
An American/TWA combined timetable effective 2 Jul 01 does show nonstop 757 services from STT to BOS/JFK/MIA
The American Trans Air timetable effective 17 Dec 94 shows one flight from STT to IND that stops in STX. The flight to STT is nonstop from IND.
For further information, see this discussion