(Bloomberg) -- The Air Force’s decision to cut 15 Lockheed Martin Corp. F-35 jets from its fiscal 2023 budget request is a temporary dip caused by delays in a $14 billion program of upgrades and a need to shift funds to new aircraft and a new engine program, service secretary Frank Kendall said.

Among recipients of those funds is the still-classified “Next Generation Air Dominance” fighter, he said.

The long-standing plan for the Air Force to buy 1,763 stealthy F-35s hasn’t changed, Kendall told reporters in advance of Monday’s release of the Biden administration’s proposed budget for the year that begins Oct. 1.

“The numbers come back up” after 2023, Kendall said. “We are not changing the goal.” He said the Air Force is “15 years into production and we’ll be building F-35s probably another 15 years.” 

Overall, the Pentagon is requesting $11 billion to buy 61 F-35s, down from a previously planned 94. In addition to 33 for the Air Force, the budget proposes 13 of the Navy’s model and 15 of the Marine Corps version.

The Air Force wants to buy fewer F-35s in the coming year in part so it can buy 12 more F-15EX aircraft from Boeing Co. than had been planned for the next budget. That would speed retirement of aging F-15C version planes. The EX model carries more ordnance than the F-35 and is estimated to be less costly to fly. 

In addition, funds will go to a new aircraft engine program and the program to build a “Next Generation Air Dominance” fighter to come after the F-35.

In the meantime, Kendall said “we’ll look for Lockheed to to make more progress” on the F-35’s Block 4 software upgrade that “has not been what we wanted.” 

The upgrade has a new hardware processor to increase the computing power and memory of the F-35. In addition, it’s intended to allow the fighters to carry new AIM-9X Block II air-to-air missiles, all-weather Small Diameter Bomb II munitions, radar-killing AARGM-ER missiles, several allied-produced bombs and the B-61 nuclear bomb. 

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