Conditioning Military Aid and the Old Argument Over Leverage on Allies

In the summer of 1982, Israeli forces were besieging West Beirut, where the Palestine Liberation Organization had its headquarters among hundreds of thousands of Lebanese and Palestinian civilians. Reports reached Washington that Israel was using American-made cluster munitions, bombs that scatter dozens of small bomblets over a wide area, in populated parts of Lebanon. Under the agreements that governed their sale, those weapons were supposed to be used only in narrow circumstances. In July, the administration of Ronald Reagan, hardly anyone's idea of a soft-on-defense president, suspended further shipments of cluster shells to Israel. The suspension lasted for years. It is a small episode in a huge war, and it is a useful place to begin, because it shows that the argument over attaching conditions to military aid is not a new invention of the American left. It is an old American argument, made by presidents of both parties, about what the United States owes its allies and what it owes its own laws.

In short: American law already conditions arms transfers in several ways, and presidents of both parties, including Reagan in 1982, George H.W. Bush in 1991 and Joe Biden in 2024, have at times slowed or paused aid to press an ally. The case for conditions rests on law, complicity and leverage; the case against rests on credibility, deterrence and the limits of influence. This post lays out both and makes an argument.

The law that already exists

Before the politics, the plumbing. Most people assume American weapons go to allies with no strings. That is not true on paper.

The Arms Export Control Act limits the purposes for which American-supplied defense articles may be used, generally to legitimate self-defense, internal security and a few others, and it requires reports to Congress if a substantial violation may have occurred. The Foreign Assistance Act contains Section 502B, which bars security assistance to governments engaged in a consistent pattern of gross human rights violations, and Section 620I, which bars it to countries restricting US humanitarian aid. The Leahy laws bar aid to specific foreign units credibly implicated in gross violations; that rule has its own post on this blog. Individual weapons sales carry agreements about how they may be used, which is what Reagan's 1982 decision relied on.

So the real debate is rarely about whether conditions should exist. It is about whether the conditions already in law should be enforced, and whether new ones should be written for specific situations.

A short history of presidents using leverage

The Reagan suspension was not the only time an American president applied pressure on Israel or other partners.

In 1981, after Israel bombed Iraq's Osirak nuclear reactor, the Reagan administration briefly delayed delivery of F-16 fighter jets. In 1991, President George H.W. Bush and his secretary of state, James Baker, held up a request from Israel for about $10 billion in loan guarantees to help absorb immigrants from the former Soviet Union, because they wanted assurances the money would not support settlement expansion in the occupied territories. The fight was bitter, and it became an issue in Israel's 1992 election. The guarantees were later approved with conditions under a new Israeli government.

The pattern extends well beyond Israel. Congress has for years tied part of Egypt's military aid to human rights conditions, with a national security waiver that administrations have frequently used. Early in his term, President Biden ended US support for offensive operations in the Saudi-led war in Yemen and paused some munitions sales to Saudi Arabia, a policy later relaxed. In May 2024 he paused a shipment of 2,000-pound bombs to Israel over concerns about their use in densely populated Rafah, while continuing other deliveries. The Trump administration released those bombs in early 2025.

In November 2024, Senator Bernie Sanders forced votes on joint resolutions to block certain arms sales to Israel. They failed, with only a minority of Democrats supporting them. Later votes in 2025 drew a larger share of Democratic senators, a sign that the party's position was shifting, though the resolutions still failed.

What this history shows is that conditioning or delaying aid is a normal, if rarely used, tool of American statecraft. It has been used by Republicans and Democrats, against friends as well as adversaries, and usually in a limited, targeted way.

The case for conditions

Here are the strongest arguments for attaching and enforcing conditions on military aid.

It is the law. The conditions described above were passed by Congress and signed by presidents. A government that ignores its own statutes when they become inconvenient is not following the rule of law. On this view, the burden is on the officials who refuse to apply existing law, not on those asking them to.

Complicity. When American weapons are used in attacks that violate humanitarian law, the United States shares responsibility, morally and potentially legally. Taxpayers have a right to insist their money not pay for war crimes.

Leverage works sometimes. Aid is one of the few tools that changes a partner's calculations. The 1991 loan guarantee fight did shape Israeli politics. Pressure has, at moments, opened border crossings for humanitarian aid. Conditions that are clear, specific and enforced tell a partner exactly what will happen if a line is crossed.

Credibility elsewhere. The United States asks Russia to respect the laws of war in Ukraine and criticizes abuses by adversaries around the world. If it never applies the same standards to friends, those arguments ring hollow, especially in the countries of the Global South whose support it seeks.

The case against

The other side's arguments are serious, and they deserve to be heard in their strongest form.

Reliability. Alliances depend on partners believing American support is dependable. Aid that can be paused mid-war may encourage partners to buy weapons elsewhere or to develop their own, reducing American influence rather than increasing it.

Deterrence. Public disputes between the United States and an ally can signal weakness to adversaries. Supporters of Israel argued, for example, that any visible gap between Washington and Jerusalem would be exploited by Iran and its allied armed groups, including Hezbollah and the Houthis.

Security needs are real. Israel faces armed groups and a regional state that have openly called for its destruction. Other partners face their own existential threats. Conditions that reduce a partner's ability to defend itself could cost civilian lives too.

Leverage often fails. History offers many cases in which pressure did not change behaviour and simply damaged relationships. Partners fighting wars they consider existential do not easily yield to outside conditions.

Private channels may work better. Diplomats often argue that quiet pressure achieves more than public conditions that force a partner to stand firm for domestic reasons.

Who actually decides

There is a constitutional question underneath all of this, and it explains why the debate so often ends in frustration.

Congress holds the power of the purse. It appropriates military aid, writes the conditions into law and can change them at any time. But day-to-day decisions about which weapons go where, and when, belong to the executive branch, which interprets and applies those conditions.

For arms sales, the Arms Export Control Act requires the executive to notify Congress of major sales before they go ahead. Congress can then try to block a sale by passing a joint resolution of disapproval. The catch is that, since the Supreme Court struck down the so-called legislative veto in 1983 in INS v. Chadha, such resolutions are ordinary legislation: they must pass both chambers and survive a presidential veto. That means blocking a sale the president wants in practice requires a two-thirds majority in both houses. In 2019 Congress passed resolutions to block arms sales to Saudi Arabia and the United Arab Emirates, and President Trump vetoed them; the Senate did not override.

Informal mechanisms matter as well. By custom, the leaders of the foreign affairs committees in both chambers get a preview of proposed major sales before formal notification, and a senior member can place a hold that delays a sale while concerns are discussed. Those holds have been used by members of both parties, sometimes for months.

The upshot is that Congress has strong tools on paper and weak ones in practice, unless a large bipartisan majority agrees. That is why so much of the fight focuses on enforcing laws already on the books, which the executive can do on its own, and why public pressure on individual members matters: a hold, a letter or a public statement from a key senator can change the timing of a decision even when a vote would fail.

Weighing the arguments

Here is the argument, and it is opinion.

The strongest point against conditions is the reliability argument, and it is right as far as it goes. A partner needs to know that the United States will not abandon it to its enemies. But conditions tied to the conduct of a war are not abandonment. They distinguish between helping an ally defend itself and supplying any weapon for any use. Reagan understood that distinction in 1982, and no serious person thought he had abandoned Israel.

The deterrence argument is weaker than it sounds. Adversaries watch American capabilities and resolve, not whether a particular shipment of particular bombs was delayed. The Biden pause in 2024 did not lead Iran or Hezbollah to conclude that the United States would not defend Israel; American forces helped intercept Iranian missile and drone attacks on Israel that same year.

The claim that leverage fails is partly true, but it cuts both ways. Leverage that is never used is no leverage at all. A partner that knows conditions will never be enforced has no reason to change anything.

There is also a self-criticism progressives should accept. The movement for conditions has sometimes made maximal demands, such as ending all military aid to a country immediately, that cannot pass Congress and alienate potential allies, when targeted conditions tied to existing law could have won broader support. The most effective version of this argument is narrow: enforce the laws already on the books, apply them the same way to every recipient, and report publicly on how they are enforced.

What conditions could look like

If you accept that conditions should be enforced, what does a sensible version look like? Several proposals have circulated in Congress in recent years.

• Use restrictions tied to existing law, such as requiring that recipients certify compliance with humanitarian law and do not restrict US-backed humanitarian aid, with consequences if they do.
• Reporting requirements that make the executive branch tell Congress, in specific terms, how American weapons have been used and whether credible allegations have been investigated.
• Category limits on particular weapons that are especially dangerous to civilians in dense areas, such as very large bombs or cluster munitions.
• Enforcement of the Leahy laws through better-funded vetting and public data.

None of these would end support for any partner. All of them would make American aid more consistent with American law.

The 2016 memorandum of understanding between the United States and Israel provides $38 billion in military aid over fiscal years 2019 through 2028. Negotiations over what comes after it will be one of the most important arenas for this debate in the coming years. Our Pentagon and militarism topic page follows that debate along with the broader arms trade.

The people on both ends

Arguments about leverage can sound abstract, but they are about people. They are about the civilians in a dense city under bombardment, whose survival may depend on whether a large bomb or a smaller, more precise one is used, or whether an aid crossing opens. They are about the soldiers and families of an ally facing real threats, who need to know that help will come. And they are about American taxpayers, many of whom want their government to support allies and also want their money not to pay for atrocities. Those wishes are not contradictory. A carefully designed system of conditions is what holding both of them looks like. It asks more of officials than a blank cheque or a blanket cutoff would, and that extra work is the price of taking both commitments seriously.

What you can do

• Call your senators before the next arms vote. Joint resolutions to block arms sales come to the Senate floor regularly. The representatives page finds your senators and representative from your address, with phone numbers, contact forms and their latest votes. Ask them to support enforcing existing law on arms transfers equally for every recipient.
• Read the recorded votes yourself. The Congress votes and bills page shows how each member voted on arms sales resolutions and related bills.
• Check where your members stand with their party. The party unity page shows how often each Democrat votes with the party, useful context when a member breaks ranks on arms votes.
• Follow the next aid agreement. The current memorandum with Israel runs through 2028. Watch the human rights and foreign aid page for reporting on its renewal and on conditions for other recipients.
• Argue the narrow version. When friends or relatives push back, skip the slogans and ask a single question: should American law on weapons apply the same way to every country that receives them? Most people, whatever their views on a particular war, will say yes, and that shared answer is where a real conversation about conditions can begin.