The UK is "on track" to have its own American football franchise within six years, says NFL spokesman Mark Waller.
London's Wembley Stadium has hosted regular-season NFL games since 2007, the Jacksonville Jaguars playing one home game a season there since 2013.
But the sport's governing body says it "fundamentally believes" there will be a permanent franchise by 2022.
"The fan base is big enough and passionate enough that it can support a franchise," said Waller.
"I felt in 2007 it was always a 15-year journey. I think we're on track to deliver that. I fundamentally believe we will deliver that."
Each of the three regular-season games at Wembley in 2015 attracted crowds of more than 80,000, and the Jaguars are contracted to continue the arrangement until 2020.
The team's links with London are strengthened by Pakistani businessman Shahid Khan, who owns the Florida-based side and Championship club Fulham FC.
However, Khan said in 2014 that he had "no plans" to move the Jaguars permanently to London.
Waller - the NFL's executive vice-chairman international - said a permanent UK franchise would offer American football an advantage over other US sports in expanding its reach beyond the States.
"We are in a unique position as a sport because of the way our season is structured - we only play one game a week,'' he said. "It's not something other American sports could do."
This autumn, two regular-season matches will be played at Wembley, while Twickenham will host its first NFL game.
|NFL International Series 2016|
|Jacksonville Jaguars v Indianapolis Colts, Wembley Stadium, London, Sunday, 2 October|
|Los Angeles Rams v New York Giants, Twickenham Stadium, London, Sunday, 23 October|
|Cincinnati Bengals v Washington Redskins, Wembley Stadium, London, Sunday 30 October|