BANGOR — Bangor International Airport laid off 15 employees Thursday and more layoffs are expected over the next two weeks, airport Director Tony Caruso said Thursday morning.

Caruso said more layoffs will be announced through next week. At that point, the airport will re-evaluate and determine what other changes might be needed to solidify its finances.

Caruso declined to say how many employees he expects to lose their jobs.

The cuts will be the “hardest thing I’ve had to do since I started at the airport,” Caruso said.

Most of the employees who received layoff notices Thursday were part-timers, some of whom may be invited to stay with the airport on an on-call basis. Caruso said the cuts would affect part-time and full-time employees, as well as union and nonunion employees, “across many divisions of the airport.”

During the past decade, the airport has served as a refueling point for more than 6,000 military charter flights. Those flights served as a significant revenue stream for the airport. Each time a military flight landed at the airport, BGR took in money for ground handling, passenger handling, gate use, fuel and service and maintenance equipment for the planes.

“We’ve had the privilege to work with these military flights for over a decade, but we knew eventually that business would start to go away,” Caruso said.

As the wars in the Middle East have wound down, the airport saw fewer and fewer military flights on the tarmac. That meant a decline in revenue. The airport has seen a 75 percent drop in the number of military flights since 2010, but the most significant hit came during 2012-2013, when the airport saw a 55 percent decrease.

Caruso said it’s difficult to pinpoint the monetary impact the decrease had on the airport because the military flight flow is unpredictable and varies year-to-year and month-to-month, but the reduction in flights has created fiscal concerns that call for changes.

Airport budget and employment totals were not immediately available.

As military action overseas continues to wind down, the airport is looking to bolster the revenue it receives from other sources, the director said. The airport has several new tenants, including Maine State Police, which moved its Orono barracks to Bangor, and C&L Aerospace, which is expanding its Bangor hub, and will continue to focus on developing those sorts of revenue streams, according to Caruso.

Caruso also said that the airport saw 5 percent growth in passenger numbers during the past year and hopes to continue to push that positive trend.

Caruso said he doesn’t expect passengers will see any major changes resulting from the lost and reduced positions.