Paul worked for State’s Bureau of Political-Military Affairs, according to his statement and his LinkedIn profile. The office manages defense relationships with U.S. allies and oversees the transfers of weapons and arms. The Huffington Post reported the news earlier on Wednesday.

His decision comes as the Biden administration has been surging weapons and munitions to Israel, a longtime key ally in the Middle East, following the Palestinian militant group Hamas’ surprise attack against the country earlier this month. But the war has also been accompanied by emotional and sometimes vitriolic responses from a divided public regarding America’s allyship with Israel through the longstanding conflict in the region — division expressed in events ranging from high-profile public protests to outbursts on college campuses.

President Joe Biden, whose Democratic Party has increasingly expressed sympathy for the Palestinian people, has been threading a needle over the situation. While showing a whole-of-government support to the United States’ longtime friend, he has also sought to express concern that Israel act humanely toward the Gaza Strip — a territory where it has indicated it will soon begin a ground invasion.

“This Administration’s response — and much of Congress’ as well — is an impulsive reaction built on confirmation bias, political convenience, intellectual bankruptcy, and bureaucratic inertia,” Paul wrote in his statement. “That is to say, it is immensely disappointing, and entirely unsurprising.”

During a trip to Israel on Wednesday, Biden announced $100 million in humanitarian aid to Gaza and the Israeli-occupied West Bank.

Paul did not immediately respond to a request for comment on Wednesday night. The State Department declined to comment.