The airline said the flight had left Toronto at 4:30 p.m. en route to Cuba when it was disrupted by "two unruly female passengers."
Sunwing vice-president Janine Chapman said the passengers had consumed a "significant quantity of their duty free alcohol purchase in the lavatory."
She said they lit a cigarette, triggering the smoke alarm, and "proceeded to get into a physical altercation with each other and made a threat against the aircraft."
Chapman added in an email to The Canadian Press that the threat was considered non-credible given the condition of the passengers.
NORAD said it scrambled two CF-18 fighter jets based out of Bagotville, Que., to escort Flight 656 back to Toronto.
Major Julie Roberge, a spokeswoman for NORAD based in Colorado Springs, Colo., said the CF-18s met the aircraft at the Canadian border and did not venture into American airspace.
She said the pilot had decided to turn the plane around over South Carolina and ‘‘that's when NORAD got involved,‘‘ adding there was no escort in U.S. airspace.
Roberge said the aircraft landed at Pearson at about 8:30 p.m. and that the CF-18 escort lasted just four minutes. She called the military escort a precautionary measure and a standard procedure in such incidents.
NORAD also used two American F-16 fighter jets based out of Toledo, Ohio in late July as a precautionary to escort another Sunwing flight as it returned to Toronto.
Peel Region police took the two unidentified women into custody once the aircraft arrived at Pearson.
There was no word on what charges might be laid against them. Peel police said they would provide an update later Thursday morning.
Sunwing said the flight was scheduled to resume its flight to Cuba at about 11 p.m. with a new flight crew.