RUTHFULLY YOURS

While President Trump has made many legally controversial decisions during his first two months as president, his recent decision to order large-scale attacks on Houthi forces in Yemen is not one of them. To be sure, critics such as former congressman Justin Amash have argued that this attack requires prior congressional approval, and Iran has already called it a violation of the U.N. Charter. But most of Trump’s opponents are focusing their attacks elsewhere.

While Trump might be tempted therefore to simply ignore those critics, the Yemen crisis is a golden opportunity for his administration to advance and strengthen an important precedent in U.S. constitutional and international law that fits comfortably with his America First agenda. Where a foreign state is unwilling or unable to take appropriate action to stop attacks on U.S. maritime commerce, the president of the United States has the authority to attack that state, or the bad actors in that state, in retaliation for their attacks and to destroy their ability to conduct future attacks. It is not impossible that President Trump will soon face similar threats to U.S. maritime commerce in other strategic waterways such as the Persian Gulf or the Taiwan Strait, so it is crucial for the Trump administration to explain why its actions are legally grounded in the U.S. Constitution and fully permissible under international law in case it needs to take similar action to defend U.S maritime commerce in those, or other, crucial waterways.

First, even the strongest defenders of congressional supremacy in war powers have long endorsed the president’s inherent authority to use force to defend America abroad, whether or not Congress has authorized it. At the Constitutional Convention, James Madison’s notes indicated that the president should have the power to “repel sudden attacks.” This defensive power has evolved over the centuries to embrace repelling attacks on Americans, and Americans’ maritime commerce, outside the U.S. as well.

For instance, President Lincoln authorized a U.S. Navy ship to join a multinational force to punish rebellious Japanese forces that had attacked international settlements in Japan and were threatening to block navigation through the Strait of Shimonoseki. Without any authorization from Congress, the U.S. Navy ship joined in the bombardment of Japanese shore batteries until the rebellious Japanese forces were subdued and the Japanese imperial government agreed to pay compensation and guarantee safe passage. President Grover Cleveland similarly did not ask Congress before dispatching a U.S. naval squadron to protect U.S. shipping, by force if necessary, due to threats by Brazilian revolutionaries to blockade the harbor at Rio de Janeiro. Most dramatically, in the months prior to the outbreak of World War II, President Roosevelt declared two-thirds of the North Atlantic a “defensive area” and authorized U.S. naval forces to “shoot on sight” any German submarines they encountered that threatened U.S. commerce heading to wartime Britain.

In the 1980s, President Reagan authorized the U.S. Navy to protect Kuwaiti oil tankers reflagged with American ensigns from Iranian attacks. When the USS Samuel B. Roberts struck an Iranian mine in April 1988, Reagan ordered Operation Praying Mantis, destroying Iranian naval vessels and oil platforms without seeking congressional authorization. The operation was justified as protecting American vessels exercising freedom of navigation in international waters — precisely the same justification available today.

Importantly, these examples confirm that the power to defend U.S. lives, property, and shipping is not limited to purely defensive measure such as shooting down Houthi missiles. Instead, U.S. practice has long authorized retaliations and other punitive actions to deter future attacks. In 1998, President Clinton authorized missile strikes on Iraq in retaliation for the Saddam Hussein regime’s attempted assassination of President George H. W. Bush and in Afghanistan in retaliation for bombings of U.S. embassies in Kenya and Tanzania. In both cases, the U.S. retaliatory response took place well after the original attacks occurred. Clinton did not ask, nor did he receive, any congressional authorization.

The president’s constitutional authority in this area has been affirmed by the Department of Justice’s Office of Legal Counsel, the key office for determining positions on questions of constitutional law for the U.S. government, across administrations of both parties. For instance, President Bush’s Office of Legal Counsel argued in 2001 that presidents had the authority to retaliate against “any person, organization, or state suspected of involvement in terrorist attacks on the United States, but also against foreign states suspected of harboring or supporting such organizations” whether or not Congress authorized such attacks. President Obama’s Office of Legal Counsel opined in 2011 that “Presidents have repeatedly deployed military forces abroad to protect U.S. persons and property from attack or threat of attack. This practice has extended over many decades and many presidencies.”

Critics such as Senator Tim Kaine (D., Va.) have argued that the 1973 War Powers Resolution restricts the president’s authority. But even this statute acknowledges the president’s power to introduce armed forces into hostilities in “a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.” It is not difficult to read this language to include attacks on American-flagged vessels or threats to freedom of navigation in international waterways where American commerce flows. In any event, the War Powers Resolution does not purport to ban any presidential action until at least 60 days from its initiation.

It is also important that the Trump administration ground the legality of its Houthi attacks as an act of self-defense consistent with Article 51 of the U.N. Charter. While some countries have advanced a very narrow definition of self-defense in international law to purely defensive measures against attacks on one’s own territory, the U.S. has long asserted a much broader principle that allows states to use force abroad to protect its nationals and their property when a target state (like Yemen) is either unwilling or unable to stop or prevent such attacks. While this version of self-defense remains heavily criticized by many international law scholars and states like China and Iran, the U.S. has slowly been building broad international support for this principle, especially since the attacks of September 11, 2001.

This is not an argument for unlimited presidential warmaking. Congress retains significant checks through its appropriations power and oversight functions. The War Powers Resolution requires presidential notification and establishes timeframes for continued military engagement without congressional approval. These mechanisms, even if some are of questionable constitutionality, ensure democratic accountability while preserving necessary executive flexibility. International law, while flawed, still provides important legitimating principles to limit self-defense actions to proportional responses where the target state is unwilling or unable to act.

Though President Trump’s attacks on Yemen are legally grounded, it is important that his administration make the legal case publicly and unapologetically. Defending these actions in legal terms is necessary to build and burnish the legal precedents that will undergird his, and future presidents’, actions in other theaters. For instance, Iran has frequently threatened to close the Strait of Hormuz to shipping, and China has recently made similar threats to the Taiwan Strait. Asserting today that the U.S. has a legal basis to respond militarily to such actions to restrict international commerce will help deter such actions, or at least bolster the legitimacy of any actions the president might have to take in future crises.

When American vessels traverse international waters, they carry not just cargo but our sovereign rights. The president’s authority to protect these rights from foreign aggression is not merely legal — it is essential. In today’s volatile security environment, where threats emerge and materialize rapidly, presidential authority to protect American lives, and vessels, abroad represents not constitutional overreach but legal necessity.