As more progressive Democrats implore the Biden administration to suspend its pipeline of military aid to Israel as a means of compelling a course change in Gaza, lawmakers and analysts say the law offers several tools for doing so.

U.S. leverage over Israel owes in large part to the $3.3 billion in annual security assistance Washington provides to the Jewish state, making it the largest recipient of American military aid. Israel’s growing isolation on the international stage — fallout from the staggering number of civilian casualties and an emerging famine in the Palestinian enclave — has only underscored the importance of its relationship with the United States, observers say.

The fury being felt by some lawmakers came through this week as they grilled senior national security officials during congressional budget hearings. Sen. Elizabeth Warren, D-Mass., lamented to Defense Secretary Lloyd Austin that “we are the ones” supplying Israeli forces with the bombs being used “to destroy homes and hospitals and refugee camps.”

The U.S. government provides “an extraordinary amount” of weaponry to Israel, said Brian Finucane, a senior adviser at the International Crisis Group, noting that the Biden administration has authorized more than 100 arms sales since Oct. 7, including through emergency means that bypass congressional review. “And so,” he said, “all of that gives the United States a lot of potential leverage, either by outright withholding or blocking transfers, or through the credible threat of doing so.”

If President Joe Biden wished to take such a step, he would not need new legislation. “There are a lot of laws on the books,” said Sarah Margon, director of foreign policy at the Open Society Foundations, “that can be used to restrict and condition security assistance in whole or in part.”

Here are the options:

Foreign Assistance Act

First, there’s Section 620I of the Foreign Assistance Act, an obscure law that several members of Congress have alluded to recently in their debates over Israel policy.

The law states: “No assistance shall be furnished … to any country when it is made known to the President that the government of such country prohibits or otherwise restricts, directly or indirectly, the transport or delivery of United States humanitarian assistance.”

Human rights advocates and some Democrats have pointed to the statute — and the administration’s own descriptions of the suffering in Gaza — to assert that Israel is violating the law.

Samantha Power, United States Agency for International Development administrator, told lawmakers this week that 1 in 3 children now suffers from malnutrition in north Gaza, while virtually none did before the war, and that the conditions amounted to “a famine, fundamentally.”

“The government of Israel has eyes on everything that goes into Gaza,” Power told a panel of senators. In another hearing, she emphasized that the flow of aid into and through Gaza had become so restricted that “kids are dying, when there’s food on the shelves in supermarkets just a few kilometers away.” She declined to say whether Israel was violating 620I, however.

The White House did not respond to questions about the law.

Margon said policymakers regard it as something of a “third rail” option because, if implemented, security assistance and arms sales would be cut entirely.

Leahy Laws

In theory, the so-called Leahy Laws provide a more palatable means of using security assistance for leverage. Named for former senator Patrick J. Leahy, D-Vt., the statute compels the State Department and the Pentagon to restrict assistance to specific foreign security units believed to have committed “gross violations of human rights.”

One big limitation of the Leahy Laws, however, is that most military aid flows to a given partner country without specifying intended units. Changes to the law in recent years have sought to address that loophole by requiring recipient countries to withhold assistance from any units designated by the United States as human rights violators.

But scrutinizing problematic units has always been a time-consuming, resource-intensive task, said Sarah Harrison — another senior adviser at the International Crisis Group — who worked previously on Leahy enforcement at the State Department. And in practice, the Leahy laws are inconsistently enforced, at best.

In the case of Israel, despite years of war with the Palestinians and well-documented concerns about the conduct of Israeli forces, the law has never been used to restrict weapons.

Presidential policy

Additionally, Harrison notes, Biden’s own policies could be applied. Each president develops one pertaining to U.S. weapons, known as the Convention of Arms Transfer (CAT), and Biden’s happens to be explicit about human rights. All decisions must consider the “risk that the recipient may use the arms transfer to contribute to a violation of human rights or international humanitarian law,” it says.

Earlier this year, Biden issued an additional policy, a national security memorandum, in response to pressure from Sen. Chris Van Hollen, D-Md., and other Democratic senators. Known as NSM-20, it requires U.S. arms recipients to provide assurances that they are acting in compliance with international law and facilitating, rather than restricting, humanitarian assistance.

Lawmakers have complained that Biden is neglecting the guidelines set by this policy as well.

Last week, after Israeli strikes killed a group of international humanitarian workers, Biden told Israeli Prime Minister Benjamin Netanyahu in a phone call that the U.S. approach to Israel “will be determined by our assessment of Israel’s immediate action” to address civilian harm, humanitarian suffering and the safety of aid workers in Gaza. But the administration has given no indication of what action it might take if Israel does not comply.

“I think people are rather skeptical that the executive branch is applying other laws objectively” to Israel, said Harrison. “The only way to really get them to change their behavior is for Congress to act.”

Holds and budgets

Yet beyond generating public pressure, Congress has few viable pathways to force an administration to cut off U.S. military aid to a country.

For instance, any one of the four chairs and ranking members of the House and Senate foreign relations committees has the option of placing a temporary hold on the forthcoming sale or transfer of U.S. weapons to a foreign country — an authority invoked previously to withhold weapons from Egypt and Turkey.

But weapons holds — while typically respected by the president — are not legally binding. President Donald Trump in 2019 blew through a congressional hold to complete an arms sale to Saudi Arabia.

Congress’s greatest power is its ability to authorize government spending. If a majority of lawmakers want to limit U.S. military assistance for Israel, they can do so when Congress passes its fiscal 2025 budget. Or they can reject a stalled supplemental funding bill that includes aid for Israel, Ukraine and several other national security priorities.

The obstacle to such a shift is simple, though: Support for Israel remains one of the most broadly popular and bipartisan foreign policies in Washington, and relatively few people in national politics want to restrict U.S. assistance in an election year with the pro-Israel lobby one of the biggest financial players.

Over the past several years, Rep. Betty McCollum (Minn.), the senior Democrat on the House Appropriations defense subcommittee, has introduced four pieces of legislation seeking to condition Israel military aid on compliance with human rights. None has become law, which she attributed in part to personal attacks by the American Israel Public Affairs Committee, the powerful pro-Israel lobbyist group spending millions of dollars this year to take on Israel’s critics

“It makes members think twice,” she said.

Ultimately, lawmakers and experts said, the power to withhold aid rests with Biden. “The bottom line,” Finucane said, “is if the U.S. government is going to use leverage … it has to be an action or credible threat from the White House itself.”

Tyler Pager contributed to this report.