For Joy Metzler, a second lieutenant in the US air force, joining the military had felt like answering a calling. An adoptee from China who was raised in a conservative Christian family, she believed she owed a debt to the United States.

But the Hamas attacks in Israel last year, and Israel’s war that followed, rocked Metzler’s convictions. Within months, she filed for conscientious objector status, one of a small number of US military personnel seeking to end their service because of their moral opposition to US support for Israel.

“I didn’t know Palestine was a place before October 7,” Metzler told the Guardian.

“All of a sudden it felt like a light clicking on for me.”

As the war in Gaza enters a second year, some disillusioned members of the US military have turned to the Vietnam war-era conscientious objector policy to terminate their military service because of religious or moral convictions.

There are few avenues to express dissent in the army. Earlier this year, Harrison Mann, an army officer assigned to the Defense Intelligence Agency resigned in protest of US support for Israel. In a far more extreme gesture, 25-year-old US airman Aaron Bushnell died after setting himself on fire outside the Israeli embassy in Washington in February.

The conscientious objector route is a seldom-invoked alternative that few service members are aware of – though some advocates say there has been an uptick in interest in the last year.

The defense department referred questions about the number of conscientious objectors to each branch of the military. A spokesperson for the air force said that it has received 42 applications since 2021 and granted 36. Applications since 7 October “are on trend with pre-conflict averages”, the spokesperson added. (The army, navy, and Marine Corps did not respond to requests for comment.)

But while the numbers remain relatively low, the war in Gaza is top of mind for those service members who have considered conscientious objector status this year, said Bill Galvin, a Vietnam-era objector and director of counseling at the Center on Conscience and War, one of a handful of groups that helps military members navigate the complex bureaucratic process.

Galvin said his group helps roughly 50 to 70 applicants a year, across military branches, and that there’s been more interest than usual this year.

The US has subsidized Israel’s war in Gaza to the tune of nearly $18bn over the last year, and is growing more deeply entangled as the conflict spills into the broader region. The Biden administration recently announced the deployment of 100 troops to Israel to man a missile defense system in anticipation of an escalation against Iran.

“Almost everyone that I’ve talked to has at least cited what’s happening in Gaza as a factor in causing them to rethink what they’re doing,” Galvin said. “Some have actually said: ‘I know that the airplane that I’m doing maintenance on is delivering weaponry to Israel and so I feel complicit.’”

Metzler said she was raised to believe that Israel is “the nation of God’s chosen people” and “terrorists were morally bankrupt people, who hate us because of who we are”.

When the war in Gaza started, the images of Palestinian civilians’ suffering disturbed her, but it wasn’t until Bushnell’s self-immolation that she started reading about the history of the conflict and the role of the US government in it. “A lot of the things I had been told about the US’s role in the world were wrong”, she said.

The war pushed Metzler to re-evaluate her time in the air force academy. She recalled laughing with her classmates as they watched footage of people running from a drone – she wasn’t sure in which country. She felt ashamed.

“I had come out of the academy glorifying the act of warfare,” she said. “There’s a certain disregard for human life that you just have to have to be a member of the military.”

Metzler learned about the conscientious objector option when she met a group of veterans at a pro-Palestine protest at the Georgia Institute of Technology, where she’s completing a master’s in aerospatial engineering.

The defense department first introduced the objector application process in 1962. Tens of thousands obtained the status over the following decade, as the Vietnam war, and a mandatory draft, sparked a mass antiwar movement. But since then, the number of applicants has fallen drastically, with many members of the military unaware that the option even exists.

“It’s not common knowledge,” said Metzler. “You don’t want to advertise to the people that are working for you that there’s a legal way for you to break your contract if you start to feel weird feelings.”

For the few who embark on it, the process is rigorous and lengthy – Metzler’s application filled 19 pages and she is still waiting for final word after filing it in July. Applicants must demonstrate that they are opposed to all wars and that their beliefs about military service changed after they enlisted. They have to interview with a chaplain and with a mental health professional before an investigating officer reviews their case and makes a recommendation to a committee that decides whether to grant the status. In the past, the military has approved about half the conscientious objector applications it received.

Larry Hebert, another US senior airman, said the process was “excruciatingly long”.

A six-year veteran, Hebert reached what he called “a moral break” as horrific images of Palestinian children resembling his own filled his TikTok.

During a leave from his service in Spain in March, he traveled to Washington and staged a hunger strike in front of the White House to highlight the plight of starving children in Gaza. He later applied for conscientious objector status, but as the wait became unbearable, he filed for voluntary separation, another avenue to legally end one’s service. When that was rejected, he took off his uniform and refused to obey orders. He was disciplined and is currently waiting to be released on administrative grounds

“I had to get out,” he said. “I didn’t want to be a part of any of it.”

Juan Bettancourt, a US airman who also filed for conscientious objector status earlier this year, told the Guardian that many of the service members he has spoken with have fear of speaking out but are privately appalled by US support for Israel. “There’s a lot of deep-seated criticism and moral disgust at the complicity of our government in the genocide in Gaza,” he said.

Because dissenting voices are so rare, the military just tries to “brush them under the rug”, Bettancourt added, noting that Bushnell’s self-immolation was portrayed by the air force exclusively as a matter of “mental health,” Bettancourt said.

The air force spokesperson wrote in a statement that the force is committed to ensuring its members “never feel compelled to resort to self-harm as a means of protest”. She added that policies like the conscientious objector process “provide a safe avenue for individuals to voice their concerns”.

But service members say voicing dissent is not easy, with a number of them incorrectly believing it’s illegal for them to do so or fearing they may get into trouble for raising questions. (Metzler, Bettancourt and Hebert all stressed they are speaking for themselves, and not on behalf of the military.)

To address that, a coalition of military personnel and veterans groups have launched an “appeal to redress” campaign, modeled after an earlier one during the Iraq war, as a way for service members to register their opposition with legislators to the US’s Israel policy.

Metzler, Bettancourt and Hebert have also launched Servicemembers for Ceasefire, offering resources for fellow members who are opposed to the war, including an explanation of the conscientious objector process.

Metzler stresses that they are not encouraging people to leave the military – they just want those with doubts to know that they have options.

“I’m not saying you have to jump ship or refuse orders,” she said. “But at the very least, pick up a book, figure out what’s going on in the world, and understand the context of what you’re doing.”