Josh Paul, who served as general manager of the "arms procurement to allies and partners" unit at the US State Department, announced his resignation in a letter posted on the professional social network LinkedIn.
According to the letter, Paul said that when he started working in the unit in question, he was aware that he would face some moral dilemmas and decided to continue to endure "as long as the benefit outweighed the harm".
"I NO LONGER WANT TO BE PART OF THIS"
Paul said that he had made moral compromises during his 11 years in office, but that the "transfer of lethal weapons to Israel" had overstepped its bounds.
"We cannot be anti-occupation and support the occupation at the same time," Paul said, adding that Israel's US-backed policy has caused great harm to both Israelis and Palestinians.
"Blindly supporting one side does not benefit either side," Paul said, pointing out that the US is repeating the mistakes of the past.
"I don't want to be a part of this anymore," Paul said, announcing his resignation from his post of 11 years.