Members of Congress have been actively debating whether and how to limit U.S. military assistance to Saudi Arabia in its war against Houthi forces in Yemen. American involvement in that region is reflected in a report by President Obama to Congress on October 14, 2016, stating that the Houthis had attacked US ships operating in international waters earlier that month. In self-defense, the United States responded with strikes against three radar facilities in Houthi-controlled territory. However, other US activities in Yemen are not defensive. They provide assistance to the Saudis, continuing into the Trump administration. There have been two major concerns. One is the President’s authority to engage in such actions without receiving specific support from Congress. The second is the number of innocent civilians who have perished in these military operations or have suffered gravely.

In a letter of February 27, 2018, William S. Castle, Acting General Counsel of the Defense Department, offered several objections to legislation that would direct the President to remove US armed forces "from hostilities in or affecting the Republic of Yemen," except US forces "engaged in operations directed at al Qaeda in the Arabian Peninsula or associated forces." In his judgment, US participation in these actions "does not constitute ‘hostilities.’" US military and intelligence support to Saudi Arabia "does not involve any introduction of US forces into hostilities." Instead, according to Castle, the United States limits its assistance to air-to-air refueling, certain intelligence support, and military advice.

He further noted that US support to the Saudi operations is guided by the view of the executive branch that "hostilities" refer to "a situation in which units of US armed forces are actively engaged in "exchanges of fire with opposing units of hostile forces." US personnel, he said, "are not engaged in any such exchanges of fire." No US forces accompany the Saudi-led coalition "when its military forces are engaged." Moreover, "US forces do not currently command, coordinate, accompany, or participate in the movement of coalition forces in counter-Houthi operations."

However the administration wants to define such words as hostilities, or distinguish between combat and non-combat, the US government has been providing important assistance to Saudi military initiatives that have led to heavy civilian casualties in Yemen. In curbing US assistance to the Saudis, members of Congress have every right to reach a judgment that American involvement contributes to those casualties and it is time to impose greater statutory limits. Castle claims that the purpose of American support for Saudi operations in Yemen is to end the war and avoid "a regional conflict, mitigating the humanitarian crisis." Instead, the humanitarian crisis has been very severe.

The United States has a long history of inflicting great cost to innocent civilians. During the war in Southeast Asia, carpet bombing resulted in the deaths of hundreds of thousands of Cambodians, Laotians, and Vietnamese men, women, and children. Even after the war concluded, civilian casualties continued because many of the bombs never exploded. This ordinance lay in the ground at great risk to civilians attempting to work the fields. Unwitting contact with these bombs led to further casualties.

The Bush II administration relied on armed drones to fight against terrorism, but technology advanced considerably by the time Barack Obama took office in January 2009. The accuracy of drones improved somewhat, but there were continued reports of drones hitting innocent individuals. At a news conference on April 1, 2016, Obama acknowledged that the use of drone strikes "wasn’t as precise as it should have been, and there’s no doubt that civilians were killed that shouldn’t have been."

In July 2016, the White House released a report estimating that the United States had inadvertently killed between 64 and 116 civilians in drone and other lethal air attacks. Those estimates applied only to airstrikes outside conventional war zones. They did not include innocent civilians killed in Afghanistan, Pakistan, Iraq, Syria, and other countries. Independent groups offered far higher numbers of innocent people killed by US drone strikes. Instead of a low of 64 deaths they released numbers in 2016 of at least 212 and as high as 325. The London-based Bureau of Investigative Journalism estimated that as of May 24, 2016, between 493 and 1,168 civilians had been killed by US drone strikes in Pakistan, Yemen, and Somalia.

On July 1, 2016, President Obama issued an executive order to address civilian casualties that resulted from US military actions. Minimizing civilian casualties, he said, "can further mission objectives; help maintain the support of partner governments and vulnerable populations, especially in the conduct of counterterrorism and counterinsurgency operations; and enhance the legitimacy and sustainability of US operations critical to our national security." Toward the end of the year, on December 6, he said "we have to fight terrorists in a way that does not create more terrorists." Before any such strike is taken outside a war zone, "there must be near certainty that no civilians will be killed or injured."

That analysis applies directly to Saudi military operations in Yemen. To the extent that innocent civilians are killed or injured, such operations will create more terrorists and greater hatred toward the United States, resulting in less security. On that ground alone, Congress has ample justification to pass legislation that prohibits any US assistance to Saudi military operations in Yemen.

Louis Fisher is Scholar in Residence at The Constitution Project at POGO. From 1970 to 2010 he served as Senior Specialist in Separation of Powers at Congressional Research Service and Specialist in Constitutional Law at the Law Library of Congress. His most recent book is President Obama: Constitutional Aspirations and Executive Actions.