The U.S. Air Force may miss its target of August 2016 to start using the Lockheed Martin Corp F-35 fighter jet in combat if Congress blocks the service's plan to retire its A-10 tank-killer aircraft, a top U.S. general said Thursday.

Air Force Lieutenant General Chris Bogdan, the Pentagon's F-35 program chief, told reporters the Air Force was counting on training experienced A-10 mechanics to help reach the total 1,100 mechanics needed to declare that the F-35 had reached "initial operational capability" or IOC.

But Congress is blocking the Air Force's plan to retire the A-10 aircraft, which means that those mechanics will be needed to maintain the older A-10 fleet, he said, adding that it would take nine to 12 months longer to train new mechanics to service the F-35 than retraining an already experienced mechanic.

Bogdan said there was also a risk of a brief delay in the July 1, 2015, target date for the Marine Corp's IOC due to a 45- to 50-day delay in flight testing caused by an engine failure that sparked a fleetwide grounding this summer, and the resulting lingering flight restrictions.

Pentagon acquisition chief Frank Kendall this week told Aviation Week that the Marine Corps could miss its target date, but Commandant General James Amos told Reuters before his retirement on Oct. 17 he still viewed that target as "doable."

Bogdan said he was concerned about the possible delay and was still hoping to avoid it, but did not expect the target date to slip by more than a couple of weeks, if at all.

George Flynn, a retired senior Marine Corps general who headed the Pentagon's joint directorate in charge of concepts, doctrine and training, said the potential impact of a shortage of mechanics underscored budget-related strains in the military.

Flynn told reporters late on Thursday that he was concerned that mandatory budget cuts were already having a negative impact on the military's "readiness" and that impact could worsen given the high number of other missions now under way, including the fight against Islamic State militants and the Ebola virus.

Bogdan said the Pentagon had approved two short- to mid-term fixes for the engine issue, and all test aircraft should be back flying without restrictions within two to three months.

He said the program was now evaluating five different options presented by engine maker Pratt & Whitney, a unit of United Technologies Corp, for a long-term solution to the issue, which occurred after a unique set of flight maneuvers led to excessive rubbing of two parts in the engine.

Bogdan said a decision on which long-term solution to adopt would be made by the end of the year. The government would cover the non-recurring engineering costs, but changes in production, tools and drawings would be funded by Pratt, he said.