Under the terms of the partnership, which is Google's first in collaboration with the D.O.D.'s Project Maven, the tech giant is helping the government use machine learning to classify images captured by drones. Nearly 4,000 employees signed an internal letter demanding Google pull out from the project, according to Bloomberg.
Some 400 technology academics and researchers from around the world have also thrown their weight behind the Google protesters' cause, publishing an open letter calling on the company to withdraw from Project Maven and commit to "not weaponizing its technology".
"The DoD contracts under consideration by Google, and similar contracts already in place at Microsoft and Amazon, signal a risky alliance between the private tech industry, now in possession of vast quantities of sensitive personal data collected from people across the globe, and one country's military", the letter states.
"We are also deeply concerned about the possible integration of Google's data on people's everyday lives with military surveillance data, and its combined application to targeted killing".
"I tried to remind myself right that Google's decisions are not my decisions".
While the likes of Amazon, Microsoft, and IBM are also working closely with the Pentagon, for example, over 30 technology companies - including Facebook and Microsoft, but not Amazon, Apple, or Alphabet - signed an Accord earlier this year stating that they would refuse to aid any government, including the USA, in carrying out cyber attacks. I'm not personally responsible for everything they do.
While the technology giant has claimed that the work was "for non-offensive purposes", previous US government memos make it clear the basis of the project is to "enhance military decision-making". In April that over 3,000 Google employees signed the petition. "But I do feel responsibility when I see something that I should escalate it", another added.
A spokesperson said: "The technology is used to flag images for human review and is meant to save lives and save people from having to do highly tedious work. We're actively discussing this important topic internally and with others as we continue to develop policies and safeguards around the development and use of our machine learning technologies".
Fortune contacted Google for comment about these resignations and will update this post if it responds.
Others expressed concerns at Google's political moves, like its sponsorship of the Conservative Political Action Conference and its struggle to address internal diversity concerns. According to Gizmodo, the resigning employees were told that that company was fleshing out a new ethics policy on AI research, but that it had yet to materialize.