In a letter address to President Obama and available to read online, Brandon Bryant, Cian Westmoreland, Stephen Lewis and Michael Hass - all former U.S. Air Force service members - are publicly denouncing the U.S.'s drone program as morally reprehensible. Drone strikes have become known for the vast number of innocent lives that they have been cut short in places like Pakistan, Yemen, Afghanistan and Somalia, and that these killings have become an important driving force for terrorism and worldwide destabilization, noted The Guardian.

The letter intends to address the fact that unmanned airstrikes have increased exponentially under Obama's administration - up by more than 800 percent since Bush's era - and the Bureau of Investigative Journalism estimates that drones have killed between 488 and 1071 innocent civilians in Pakistan, Somalia and Yemen, but its figures do not include Afghanistan, reported NBC News.

The letter links the recent attacks in Paris, as well as ISIS's widespread recruitment efforts, to the drone program. "We came to the realization that the innocent civilians we were killing
only fueled the feelings of hatred that ignited terrorism and groups like ISIS, while also serving as a fundamental recruitment tool similar to Guantanamo Bay. This administration and its predecessors have built a drone program that is one of the most devastating driving forces for terrorism and destabilization around the world," they said in the letter.

All four of the former drone operators now live with severe PTSD (Post-Traumatic Stress Disorder), and say that they have been betrayed by the government of the country they pledged to serve, as some of them are homeless and all of them lack the means to get appropriate care, medical and otherwise, noted NBC and the letter. Lewis remembers having to drink himself to sleep nightly due to the guilt of killing innocent people.

The men express their fear about speaking out and being persecuted like other truth-tellers Julian Assange and Edward Snowden, so they are being represented by attorney Jesselyn Radack, director of national security and human rights at the nonprofit ExposeFacts, reported Common Dreams.