By Doug Cameron and Paul Sonne

Senior U.S. Air Force officials said there were opportunities for the incoming administration to cut the cost of the huge F-35 combat jet program, but warned it may be tougher than expected and shouldn't dilute the advanced plane's capabilities.

President-elect Donald Trump has said the costs of the F-35 program led by Lockheed Martin Corp. are "out of control", taking aim at the Pentagon's most expensive program in a series of tweets and speeches.

"This program is not out of control," said Lt. Gen. Chris Bogdan, the military head of the F-35 program, in a media briefing on Monday.

Mr. Bogdan said he recognized how the F-35 could be classed as troubled because of past problems, but maintained it had broadly met cost and schedule targets since being reset in 2011.

The Pentagon plans to buy more than 2,400 of the planes to replace many of its combat jets, but they are entering service years late and purchase costs doubled to almost $400 billion because of earlier design and production problems. Including operating expenses, the bill is estimated to top $1 trillion over the next 50 years. The plane is also being bought by a number of overseas governments.

Separately, the civilian head of the U.S. Air Force said earlier Monday that the incoming administration may find it tougher than they expected to bring down the cost of big military programs such as the F-35.

"It's not quite as easy as it seems to get these costs down," Air Force Secretary Deborah Lee James said during an event organized by the Atlantic Council, a think tank.

Ms. James said she and other Pentagon leaders had briefed members of the transition team in recent weeks, and said its understanding of Air Force requirements and the complexity of the buying process would continue to develop. She added some of the team are still in the process of securing the security clearances needed to assess programs.

Lt. Gen. Bogdan said his team hadn't met transition officials, but said costs could be cut further beyond ongoing efforts that reduced the per-plane price of the model used by the Air Force to $102 million under terms imposed on Lockheed.

"Our job is to give the new administration the good, the bad and the ugly about this program." he said. "I'm not a salesman for the F-35."

Lt. Gen. Bogdan said reducing the capabilities of the plane -- which can evade sophisticated radar and act as a flying command post -- should not be reduced to cut costs.

"We know what this airplane needs to do to keep us safe," he said.

Lockheed and other suppliers such as Northrop Grumman Corp. and BAE Systems PLC are already investing to reduce production costs, and Lt. Gen. Bogdan said more competition between suppliers and multiyear buys of the plane to generate economies of scale were two avenues to explore further.

International buyers of the plane -- which include the U.K., Israel and Japan -- are already discussing such a block buy, as is the Pentagon, which currently purchases a number of planes on an annual basis.

Lockheed remains embroiled in an unusual battle with the Pentagon over what the government is willing to pay for F-35 jet fighters, a situation that could depress profits at the world's largest defense contractor.

The Pentagon last month ended more than year of talks with Lockheed and said it was imposing a new $6.1 billion deal for the next batch of 57 planes that start delivering next year.

Write to Doug Cameron at doug.cameron@wsj.com and Paul Sonne at paul.sonne@wsj.com

(END) Dow Jones Newswires

December 19, 2016 15:40 ET (20:40 GMT)

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