In an interview, Sheline said her focus had been promoting human rights in the Middle East and North Africa, work that was complicated by Israel’s war in Gaza and a host of accompanying moral, legal, security and diplomatic implications for the United States. Sheline said she tried to raise concerns internally with dissent cables and at staff forums but eventually concluded that it was pointless “as long as the U.S. continues to send a steady stream of weapons to Israel.”

“I wasn’t able to really do my job anymore,” Sheline said. “Trying to advocate for human rights just became impossible.”

Sheline’s departure is the most significant protest resignation of the Gaza conflict since the exit of Josh Paul, who was a senior State Department official involved in arms transfers to foreign governments.

In a statement to The Washington Post, Paul commended Sheline for having the courage to resign, noting that she is leaving the Bureau of Democracy, Human Rights and Labor, which is tasked with championing “universal values, including respect for the rule of law, democratic institutions and human rights,” according to the State Department website.

“When the staff of that bureau feel that there is no more they can do, it speaks volumes about the Biden administration’s disregard for the laws, policies and basic humanity of American foreign policy that the bureau exists to advance,” Paul said.

Sheline said she had not planned to resign publicly — “I didn’t think I was senior enough to” — but decided to speak up at the request of colleagues who told her they wanted to resign but couldn’t because of financial or family considerations.

Sheline said that despite the support she has received at the State Department, “there are plenty of people who wouldn’t agree with my point of view.”

At internal listening sessions on the war, she said, some employees “stand up and say, ‘I appreciate everything the U.S. government and the State Department are doing for Israel, and I really support it.’” Those comments typically get pushback from others in the audience, she added.

At one of those meetings, Sheline recalled, she asked about administration priorities — competition with China, human rights, climate change — that she felt were being undermined by blank-check support for Israel.

“My question was: Why is this support for Israel seen as more important than all of these other, arguably very significant priorities?” she said. “I still don’t feel like I have a great answer as to why.”

Only a handful of officials have left government over the war. For months, however, workers have telegraphed discontent over Israel policy in other ways.

At the State Department, officials have written multiple cables on Gaza within the dissent channel, a Vietnam War-era mechanism for internal protest.

At the U.S. Agency for International Development, hundreds of employees endorsed a letter in November calling for the Biden administration to use its leverage to initiate a cease-fire. Other officials have challenged agency leaders during public events.

In February, an active-duty member of the U.S. Air Force set himself on fire outside the Israeli Embassy in Washington after saying he could “no longer be complicit in genocide.” He died from his injuries.

Scores of officials across the federal workforce participate in private chat groups for organizing fundraising efforts, public demonstrations and venting about U.S. policy.

Despite the dissent, the Biden administration has maintained its military support for Israel’s campaign in Gaza, authorizing the transfer of thousands of bombs and other munitions since Oct. 7. But the administration’s tone has begun to change.

The State Department now routinely expresses concern about the bloodshed: 32,000 Palestinians have been killed, according to the Gaza Health Ministry, since the war began in response to the cross-border attack in which Hamas militants killed 1,200 people in Israel and took at least 250 hostage. The administration has also increased public pressure on Israel to allow more humanitarian assistance into Gaza, which aid groups warn is on the brink of famine.

On Monday, the administration chose not to veto a U.N. Security Council resolution calling for an immediate cease-fire during the remaining weeks of Ramadan and the release of all hostages — a move that angered Israeli Prime Minister Benjamin Netanyahu, who canceled a planned trip of top aides to Washington.

The bureau where Sheline worked has faced scrutiny from some members of Congress wary of any part of the U.S. government that might criticize Israel. President Biden’s pick to lead the bureau, Sarah Margon, withdrew her nomination as assistant secretary last year after a vote on her confirmation stalled for more than 18 months. The top Republican on the committee, Sen. James E. Risch (Idaho), had voiced concerns that she was insufficiently pro-Israel, a charge that her supporters, including prominent Jewish foreign policy professionals, disputed.

Sheline took a circuitous route to the State Department. She grew up in North Carolina and has written that her interest in foreign policy began after the Sept. 11, 2001, attacks, which occurred when she was a sophomore in high school. She pursued studies in conflict resolution, focusing on the Middle East, and later took Arabic classes in Egypt and other countries. For her academic work on the region’s monarchies, she made research trips to Morocco, Jordan, Oman and Saudi Arabia.

During this period, Sheline worked as a researcher at the Quincy Institute for Responsible Statecraft, a think tank that promotes a U.S. “foreign policy that emphasizes military restraint and diplomatic engagement,” according to its website. There, she criticized the U.S. policy of sending arms to Arab allies despite their well-documented human rights abuses. She said she had not planned on a federal career but was awarded a fellowship that came with the condition that she serve a year in the government afterward.

Last spring, Sheline was hired by the State Department in the Near Eastern Affairs section of the bureau that compiles an annual country-by-country report on the state of human rights around the world. She worked mostly on North Africa, liaising with activists and civic groups to promote democratic values such as freedom of assembly and a free press.

That work has become nearly impossible, Sheline said, with partners in the region incensed by the continued flow of U.S. arms to Israel despite the staggering toll of the war. Some activist groups have stopped talking to American personnel, Sheline said.

“If they are willing to engage, they mostly want to talk about Gaza rather than the fact that they are also dealing with extreme repression or threats of imprisonment,” Sheline said of civil society groups in the region. “The first point they bring up is: How is this happening?”

Sheline said she had planned to stay on at State until the Gaza war changed her mind. She notified her supervisors six weeks ago that she would be resigning once she had completed her year of service. She plans to work on a book based on her academic research, though she is still coming to grips with the long-term price she is likely to pay for taking a stand on a politically toxic issue.

“I know I’m foreclosing any sort of future at the State Department, or maybe even in the U.S. government, which I think is unfortunate because I really valued the work that I was doing there,” Sheline said.

As someone with “a daughter and a mortgage,” Sheline said, she understands the financial risk of quitting, one of many reasons her former colleagues cited for choosing to stay and fight for policy changes from inside government.

“They really believe in the mission,” Sheline said of her State Department colleagues. “They believe in America, and what this country says it’s supposed to stand for.”