The top Army and Marine Corps generals say they're concerned about an increasing number of major military aircraft accidents.

During congressional testimony Wednesday, Marine Corps Commandant Gen. Robert Neller says part of the problem is that his service doesn't have enough aircraft to meet the training requirements for the entire force.

Gen. Mark Milley, the Army chief of staff, says the spike has gotten his attention.

GOP Rep. Mac Thornberry of Texas, the chairman of the House Armed Services Committee, says Defense Department data show that the average number of major accidents over the past 10 years is 2.15 mishaps per 100,000 flying hours.

But the Marine Corps accident rate has increased from 2.67 per 100,000 hours in the 2014 budget year to 3.96 per 100,000 hours in 2016.