Lawmakers on both sides of the Atlantic are now openly suggesting that their countries cut back on their F-35 purchases. Mounting costs and numerous delays have made the West’s ultimate fifth-generation fighter jet increasingly unpopular.

Across Europe, NATO countries are forced to cut defense spending. The British in particular are facing dramatic cutbacks while they were the only so-called Level 1 partner in the Joint Strike Fighter program, supposed to cover approximately 10 percent of total development costs, or $2.5 billion.

Since Britain announced that it would reduce the number of F-35s it will acquire, the Level 2 partners, Italy and the Netherlands, contributing $1 billion and $800 million respectively, have been critical. In both nations, there are parliamentarians who favor pulling out of the project altogether. The Dutch government has indicated that if individual aircraft costs indeed rise by up to 20 percent, it will not be able to afford the 85 planes it originally intended to acquire to replace its current fleet of one hundred F-16s.

In the United States, the Joint Strike Fighter is supposed to replace the F-16, the A-10 as well as most F/A-18s. The Air Force and Navy fly many hundreds of these planes and were expecting to buy more than 2,400 new fighter jets. The individual price tag of each plane has skyrocketed however. It is now estimated that the F-35 will cost $133 million a piece and be far more expensive to maintain than existing warplanes. Last year, the Department of Defense disclosed that the entire program had exceeded its original cost estimate by more than 50 percent. Total expenditures could now reach up to $1 trillion.

Delays have forced the military to buy upgraded versions of older aircraft meanwhile to fill the gaps. Other nations, including Australia and Israel, will likely face similar “fighter gaps” and ask to lease American jets to make up for it — putting further pressure on the United States Air Force and Navy.

The Pentagon has repeatedly insisted that the cost overruns are “unacceptable” and lawmakers agree. “We need to know that the program is going to bring that number down,” said Senator John McCain, ranking member of the Armed Services Committee, last month.

While some politicians and defense analysts have proposed to terminate the program, the Pentagon insists that it still needs the new fighter jet. “We must field a next generation strike fighter, the F-35, and at a cost that permits large enough numbers to replace the current fighter inventory and maintain a healthy margin of superiority over the Russians and Chinese,” said Secretary Robert Gates last week.