Employees at Google have signed a letter protesting the company’s involvement in Project Maven, the Department of Defense program that plans to use artificial intelligence (AI) in analyzing drone footage, according to the New York Times.

The letter, signed by 3,100 employees and dozens of senior engineers, was addressed to Google CEO Sundar Pichai in order to raise concern about the program, which they believe could be used to improve the accuracy of offensive drone strikes.

“We believe that Google should not be in the business of war,” the letter reads. “Therefore we ask that Project Maven be cancelled, and that Google draft, publicize and enforce a clear policy stating that neither Google nor its contractors will ever build warfare technology.”

Project Maven, also known as Algorithmic Warfare Cross-Functional Team, was established in April 2017 with the goal of integrating machine learning and artificial intelligence in the fight against ISIS. The program’s first mission was to develop AI that can quickly identify object classes from the incredibly large amount of footage collected by drones and other ISR assets.

The Pentagon has been signaling its intention to increase focus on defense applications for AI technology. This was reflected in the recent omnibus spending bill signed by President Trump on March 23, in which Project Maven received a large pay upgrade. The bill appropriated $131 million to the AI program, up from the $31 million that the Pentagon had requested, according to reporting from Bloomberg.

Google employees voiced their concerns about the project at a recent company-wide meeting, during which Diane Greene, who leads Google’s cloud infrastructure business, assured employees that the technology will not “operate or fly drones” and “will not be used to launch weapons,” according to a letter The Times obtained.

This was cold comfort to the Google employees.

“While this eliminates a narrow set of direct applications, the technology is being built for the military, and once it’s delivered it could easily be used to assist in these tasks,” they wrote in the letter.