ISIS has reportedly lost recruits in recent months. Above, a member loyal to the terrorist group waves an ISIS flag in Raqqa, Syria, June 29, 2014. REUTERS/Stringer

The number of foreign fighters crossing into Syria and Iraq has dropped sharply over the past year amid an intense U.S.-led campaign against the Islamic State group, Maj. Gen. Peter Gersten told Pentagon reporters. Whereas about a year ago the group was attracting up to 2,000 foreign fighters each month, these days just a fraction of that number is joining, Agence France-Presse reported him as saying.

"Now we have been fighting this enemy for a year, our estimates are down to 200 [per month], and we are actually seeing now an increase in the desertion rates of these fighters," Gersten said. "We are seeing a fracturing in their morale, we are seeing their inability to pay, we are seeing the inability to fight."

The revelation comes the same month Deputy Secretary of State Antony Blinken said the total number of fighters with the group, also known as ISIS, has hit its lowest point since the U.S. began keeping track in 2014. Gersten did not offer an estimate for the present size of ISIS’ forces. In the past, it has been placed at between 20,000 and 31,500.

ISIS has reportedly been losing ground and revenue amid bombardment by a U.S.-led coalition. Kurdish and Arab fighters — including governmental and opposition forces — have also been battling the group and have managed to retake key territory. ISIS has lost about 20 percent of the territory it once held in Syria and 40 percent in Iraq, military officials have said.

Much of the anti-ISIS campaign has also focused on targeting the group’s revenue, including oil infrastructure and cash storage facilities. Gersten said as much as $800 million in cash has been blown up.

"We are watching them try to leave Daesh. In every single way, their morale is being broken," Gersten said, using an Arabic acronym for ISIS.