The Islamic State is conscripting men in Iraq and Syria to fight against U.S.-led coalition forces amid a sharp decline in the flow of foreign fighters as the militant group faces mounting defeats, according to the coalition's deputy commander.

British Maj. Gen. Rupert Jones told Pentagon reporters Wednesday that ISIS's shrinking territorial holds have compromised the group's brand of invincibility, in turn causing recruitment numbers to plummet. In a scramble to offset battlefield losses, ISIS has been forced to conscript locals to join the fight.

Citing the final weeks in the battle for West Mosul, Jones said people weren't "walking into a recruiting office, saying, ‘Hey, I buy into your narrative, I'm all up for the fight.' Far from it. That was people facing the ghastly choice of probably being executed then and there or coming and fighting, kicking and screaming, for ISIS."

The same is now occurring in Syria, where ISIS is battling to the death to keep hold of Raqqa, once its de facto capital and primary launching pad for international attacks.

Jones, the No. 2 coalition commander, said coalition advances have "slowed to a trickle" the flow of foreign fighters, who were once streaming into Iraq and Syria at a rate of roughly 2,000 per month.

While it would be impossible to stop the flow entirely, he said successive ISIS losses have made it less attractive for sympathizers to travel to the region to fight.

"They are losing on all fronts," he said. "They are losing on the battlefield, they are losing financially, the flow of foreign fighters has slowed to a trickle. Their narrative has been so significantly discredited … People don't believe in it. They don't want to come from France, Britain, Belgium, or anywhere else to come and fight for ISIS."

The coalition estimates about 2,500 ISIS fighters remain in Raqqa, with another 2,000 in Iraq's Tal Afar, and between 5,000 to 10,000 in the Middle Euphrates River Valley region that cuts across Syria.

Echoing remarks over the weekend by Iraqi Prime Minister Haider al-Abadi, Jones said the several thousand ISIS fighters battling coalition forces now have no choice but to "surrender or die."