The Lockheed Martin F-35 Lightning II is the most advanced fighter plane ever built. It can fly at supersonic speeds, is undetectable by radar, and one version can even take off and land vertically from aircraft carriers. Sixteen years in the making, the Pentagon wants the F-35 to replace several planes used since the Vietnam era by the Air Force, Navy, and Marines.

But in December 2016, Donald Trump put the whole project in doubt with a single tweet. He criticized the project for being too expensive and called for Boeing, Lockheed Martin’s main rival, to bring him plans for a different plane. The same day, Lockheed Martin’s stock fell by 2 percent, temporarily wiping away an estimated $1.2 billion.

Trump’s grasp of policy details is often, to be generous, questionable. In the case of the F-35, however, Trump’s not wrong. The project is seven years late and 70 percent over budget. It’s been delayed by countless design flaws and malfunctions, which has caused massive cost overruns with no end in sight. Each plane could cost up to $115 million dollars, and there are still serious concerns about its durability. Some critics also question the need for a next-generation plane, given that the US military’s current fleet is already more advanced than those of Russia and China.

But at this point, the F-35 can’t be canceled. That’s because, while the plane itself may be poorly designed, how the plane is built was perfectly designed. The F-35 project was intentionally designed to have stakeholders in Congress, the economy, and the military —a group informally known as the military-industrial complex. All of them have a lot to lose if the project fails, and they will fight tooth and nail to protect Lockheed Martin no matter how poorly the project is going. It’s a strategy called political engineering, and all the major defense companies use it.

One thing every member of Congress can support is jobs in their district. So major US defense contractors spread their operations across as many states as possible, because the more districts they have employees in, the more legislators will fight to protect those jobs and the programs that support them.

That’s important, because all defense contracts, both domestic and foreign, need approval from Congress. This creates a situation where lawmakers from both parties often support whichever defense company has jobs in their district. When Lockheed Martin was competing against Boeing for the F-35 contract, many members of Congress, especially the delegation from Texas, were very vocal in their support for Lockheed Martin, which planned to assemble the F-35 in Fort Worth.

Today, Lockheed Martin claims the project supports 146,000 jobs across 46 states. This is the main reason why the F-35 has overwhelming and bipartisan support in Congress; almost everyone on Capitol Hill has jobs to protect. In addition, eight other countries, including Turkey, Italy, and Australia, have subcontractors working on the plane, and many of these countries have put in orders for their own militaries. Anything done to hurt the F-35 project could hurt the US’s relationship with those countries.

So despite long delays and cost overruns, the F-35 is clearly too important to too many people to be canceled. If it were, jobs would be lost, foreign relationships could be hurt, and the military would have no planes to replace its aging fleets. While Trump could curtail future purchases of the F-35, it’s wouldn’t be an easy fight.