US Air Force Lt. General Christopher Bogdan said that the F-35 Joint Strike Fighter "will survive in combat for decades to come."

WASHINGTON (Sputnik) — The effort to develop the F-35 Joint Strike Fighter needs to continue because the present mix of US military aircraft will not survive future combat conditions, the F-35 program’s Executive Officer, US Air Force Lt. General Christopher Bogdan, told Congress on Wednesday.

Bogdan was responding to calls by some lawmakers to cancel the expensive F-35 program and spend funds to upgrade the fourth generation legacy aircraft such as the F-16 and F-18 fighter jets.

"You can only do so much with our fourth generation fighters today," Bogdan told the US House of Representatives Armed Services Subcommittee on Air and Land Forces. "So no matter how much you upgrade them and how much you put into them, eventually they will not survive… in combat."

Instead, Bogdan said the F-35 jet "will survive in combat for decades to come."

The F-35 program has been beset by technical problems and cost overruns, pushing its expected total project cost to some $1.5 trillion over its 55-year lifespan — the most expensive US weapon program ever.

Problems with the futuristic aircraft have included flaws in its fuel and hydraulic systems, poor cockpit visibility, software glitches and freezes, faulty radar and ejection seats that do not work. The entire fleet was grounded in 2014 after an engine caught fire as a test pilot prepared to take off.