Every time President Donald Trump mentions the $110 billion arms deal he negotiated with Saudi Arabia last year, he quickly follows up, saying "It's 500,000 jobs."

But if he means new U.S. defense jobs, an internal document seen by Reuters from Lockheed Martin forecasts fewer than 1,000 positions would be created by the defense contractor, which could potentially deliver around $28 billion of goods in the deal.

Lockheed instead predicts the deal could create nearly 10,000 new jobs in Saudi Arabia, while keeping up to 18,000 existing U.S. workers busy if the whole package comes together—an outcome experts say is unlikely.

A person familiar with Raytheon's planning said if the Saudi order were executed it could help to sustain about 10,000 U.S. jobs, but the number of new jobs created would be a small percentage of that figure.

Lockheed Martin declined to comment on the Saudi package. Raytheon's Chief Financial Officer Toby O'Brien said last week that hiring overall is growing, but he did not pin it to any particular program.

The White House did not immediately respond to a request for comment.

Jobs are important to Trump. He campaigned on his ability to create American jobs, especially high-paying manufacturing ones. Meanwhile he has limited his criticism of Saudi leadership over the killing of a prominent critic because he did not want to endanger the massive arms deal.

Trump's 500,000 figure has been greeted with widespread skepticism given the five biggest U.S. defense contractors, who make nearly every item on the Saudi list, now employ 383,000 people.

Documents seen by Reuters and interviews with defense industry sources familiar with the arms package suggest that between 20,000 and 40,000 current U.S. defense industry workers could be involved in Saudi-bound production if the whole $110 billion package goes through.

Existing workers typically are experienced, skilled, who can be redeployed more easily than new hires who would require significant upfront investment in their training.

One significant caveat to any predictions on job creation is whether all of the missile defenses and radars, ships, tanks, software, bombs and other equipment listed in the full Saudi package get delivered.