Andrew Miller and Seth Binder make a good case that cutting off arms sales to other governments can be effective in influencing them:
The reluctance to use the leverage afforded by arms transfers is symptomatic of a broader pathology in U.S. foreign policy: a fixation on maintaining relationships without regard to the value they provide. Relationships are important, but the United States should receive a commensurate return on its investments. When this is not the case, the United States should not hesitate to adjust the status and intimacy of a bilateral relationship, including through the suspension of arms transfers.
When clients do things that the U.S. objects to, the U.S. can and should reduce or end the sales of weapons to those governments to influence them to change their policies. Opponents of such measures often claim that the U.S. will be losing its access and influence with these governments, but according to them the U.S. should never actually use the leverage it has with these states for fear of losing it in the future. If the U.S. is never supposed to use the influence it has with its clients, that puts the U.S. in the absurd position of enabling and encouraging reckless client behavior without having any means of reining them in. If the U.S. cannot make use of the leverage it has, it is as if it never had any in the first place.
In the case of the Saudis and Emiratis, there is substantial support in Congress for halting arms sales to these governments because of the crimes that they and their proxies have committed in Yemen with U.S.-made weapons. The use of U.S.-made weapons in the commission of war crimes is another reason for the U.S. to stop any more arms sales. The U.S. should refuse to provide the Saudis and Emiratis with more weapons that we know they will use to attack civilians because it will put pressure on these governments to scale back or halt their military campaign, but it will also ensure that the U.S. won’t be contributing to the Saudi coalition’s killing of civilians in that way any longer.
Despite being the patron and arms supplier, the U.S. frequently acts as if it is the one with the most to lose if a relationship with a reckless client goes sour. As Miller and Binder explain, this gets things backwards, since the purpose of the relationship is to provide some benefit to the U.S. Relationships with client states are not ends in themselves, but are supposed to advance U.S. security. When those relationships cease to deliver, or when they become liabilities to U.S. interests, the U.S. should be willing to use whatever leverage it has to fix that. If the client relationship can’t be salvaged and no longer benefits the U.S., that is when it should be downgraded and U.S. support should be permanently curtailed.