Naval Blockades vs. War: The Legal Distinction That Lets Presidents Act Alone

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The mechanism is surprisingly simple. Call it a quarantine instead of a blockade. Frame the operation as sanctions enforcement rather than war. Characterize the capture of a foreign leader as law enforcement instead of regime change. These aren’t semantic games—they’re the legal distinctions that let presidents bomb, seize ships, and topple governments while technically staying within the boundaries of the War Powers Resolution.

Senate Republicans and the War Powers Vote

Five Republican senators joined Democrats to advance a war powers measure that would have forced Trump to withdraw forces absent congressional approval. The five were Rand Paul of Kentucky, Susan Collins of Maine, Lisa Murkowski of Alaska, Josh Hawley of Missouri, and Todd Young of Indiana. However, Hawley and Young would reverse their positions by the time of the final vote.

Trump released a social media post declaring the five “should never be elected to office again,” accusing them of undermining national security. Secretary of State Marco Rubio started making phone calls. Personal meetings followed. By the final vote, Hawley and Young had flipped.

What changed their minds wasn’t a legal argument. It was a promise. Rubio offered a political commitment—we won’t do the thing you’re worried about—in exchange for killing a measure that would have created a legal framework. Hawley and Young accepted the trade. The measure died on a procedural vote.

What the White House Claims Isn’t War

Start with the naval blockade—except don’t call it that, because blockades are acts of war. The White House prefers “quarantine” or “sanctions enforcement.” U.S. forces have conducted operations against Venezuelan vessels. Officials claim each target was smuggling drugs or supporting terrorism. These operations were conducted as peaceful seizures and boardings without reported casualties, though they involved armed personnel and the threat of force.

In December, Trump announced a “total and complete blockade” of sanctioned oil tankers. By January 7, additional tankers were seized, including the Russian-flagged Marinera and the Panama-flagged M Sophia.

The White House’s position: none of this constitutes “war” or “hostilities” requiring approval. The naval seizures were sanctions enforcement—a legal matter, not armed force. The airstrikes were counternarcotics efforts. The blockade wasn’t a blockade at all, but a quarantine of specific sanctioned vessels.

The War Powers Resolution’s Critical Loophole

The War Powers Resolution of 1973 was supposed to prevent exactly this kind of sustained force. Passed over President Nixon’s veto, the statute requires presidents to obtain approval within 60 days of introducing armed forces into hostilities. More specifically, the resolution requires presidential notification to Congress within 48 hours of introducing forces and mandates congressional authorization to continue operations beyond 60 days (either an Authorization for Use of Military Force or a declaration of war). Without such authorization, the president must terminate the use of forces, with the understanding that withdrawal may require additional time to execute safely.

But it only applies when forces are introduced “into hostilities.” That single word—hostilities—created the loophole every president since has exploited. What constitutes hostilities? The statute doesn’t say. Is it only ground combat? Does it include airstrikes? Naval operations? Special operations forces conducting a raid? The ambiguity has proven fatal to congressional oversight.

Under international maritime law, a blockade is an act of war. It requires a formal declaration, must be enforced impartially against all vessels, and triggers the full apparatus of the laws of armed conflict. A quarantine, by contrast, is more limited—selective enforcement against specific vessels or cargo, conducted in the absence of a war declaration.

The Trump team borrowed this framework directly from the Kennedy team during the Cuban Missile Crisis. By calling it a quarantine and limiting it to specific weapons shipments, Kennedy created legal space for sustained force that technically fell short of war. Trump’s approach follows the same pattern. By targeting only sanctioned oil tankers rather than all shipping, the White House claims it’s conducting sanctions enforcement, not a wartime blockade. The selective application—we’re only stopping these specific vessels—becomes the legal distinction that supposedly keeps things below the threshold of “hostilities.”

The Justice Department’s Legal Justification

The Justice Department released a legal memo providing the official legal justification for operations. The memo’s core argument rests on a distinction between “war” and “armed conflict.” Yes, the operation would constitute an armed conflict under international humanitarian law, meaning the laws of war would apply to how it was conducted. But no, it didn’t constitute “war” in the sense meant by the Constitution requiring approval.

The operation is war for purposes of international law—which means the armed forces must follow rules about proportionality, civilian protection, and treatment of prisoners. But it’s not war for purposes of the Constitution—which means Congress has no say in whether it happens at all.

The memo cited historical precedents: Haiti in 1994, Kosovo in 2000, Libya in 2011. Each involved force lacking approval. Each had been blessed by the Office of Legal Counsel under Democratic leadership. By anchoring the operation to Democratic-era precedents, the lawyers argued this wasn’t a novel claim but the continuation of a bipartisan executive tradition.

By producing a substantial official document addressing the question, the White House created something wavering senators could point to when asked about the legal basis for their votes. The memo’s existence suggested careful deliberation, even if its reasoning stretched precedent past the breaking point.

Republican Senators Who Maintained Opposition

Three Republicans maintained their support despite Trump’s pressure and Rubio’s assurances. Rand Paul argued: “The reason the Founding Fathers gave this power to the legislature is because they wanted to make war less frequent, they wanted to make war hard to initiate, they wanted to see war more as a defensive notion, not as an offensive enterprise.” By allowing the executive to conduct sustained force that technically falls short of war, the War Powers Resolution’s gaps create the opposite effect. They make armed force easier and faster, requiring only presidential decision rather than deliberation.

Susan Collins’ vote suggested she saw through the legal framing to the underlying reality: these were armed operations conducted against a sovereign nation, and calling them something else didn’t change their fundamental character. Lisa Murkowski also maintained her position.

International Law Violations

While the Senate debated authority, international legal experts raised a different concern: the U.S. operations violated maritime law in ways that could destabilize the entire framework governing naval conduct. The country raised formal complaints in the UN Security Council. The Office of the UN High Commissioner for Human Rights issued a statement condemning the sanctions and quarantine, asserting the U.S. was “violating fundamental rules of international law.” Iran’s Foreign Ministry called the seizure of the Russian-flagged Marinera “an act of piracy.”

The legal problem stems from where the seizures occurred. The U.S. was boarding vessels in international waters—not territorial seas, not even the contiguous zone, but the high seas where freedom of navigation is supposed to prevail. The traditional legal basis for stopping ships on the high seas is limited: piracy, slave trading, statelessness, or consent of the flag state. Sanctions enforcement isn’t on that list.

The U.S. has a way around this constraint: it never ratified the UN Convention on the Law of the Sea. While the U.S. acknowledges many of UNCLOS’s principles, it’s not formally bound by them. This non-ratification creates a peculiar situation where international law experts can condemn American operations, but the U.S. faces limited formal legal consequences.

The seizure of the Marinera illustrates the complications. The ship was Russian-flagged, owned by a Turkish company, with a Georgian captain and a crew of Ukrainian, Georgian, and Russian citizens. By seizing it, the U.S. entangled its operations in the broader U.S.-Russia relationship, with Moscow viewing the seizure as piracy and demanding crew repatriation.

China’s interests were implicated too. China purchases most oil at discounted prices, and the blockade threatened to disrupt commercial relationships central to China’s resource strategy in the Western Hemisphere. The Trump team’s invocation of the Monroe Doctrine—rebranded as the “Donroe Doctrine”—signaled an intent to establish unilateral American dominance in the region, with the blockade functioning as the instrument enforcing that broader geopolitical strategy.

The Vulnerability of Political Commitments

The Rubio assurances that convinced Hawley and Young to flip their votes created a critical vulnerability: they’re political commitments, not legal constraints. If the White House decides to deploy ground troops, or determines that “circumstances don’t permit” consultation before “major operations,” what recourse do those senators have? They could introduce another war powers measure, but it would face the same procedural challenges. They could try to cut funding, but that requires action and presidential signature or veto override. They could sue in federal court, but courts have historically treated war powers disputes as political questions inappropriate for judicial consideration.

History suggests executive commitments made to secure legislative support often prove unreliable when circumstances change. Nixon committed to consulting Congress before expanding the war in Cambodia, then proceeded with bombing lacking consultation. Reagan committed to notifying Congress of intelligence efforts, then repeatedly violated those commitments. Bush made representations about the scope of torture and detention, then conducted operations exceeding those representations.

Hawley and Young may have calculated that political commitments provide adequate protection because violating them would create immediate political consequences. But that substitutes political trust for legal constraint.

The Template for Future Operations

The successful use of blockade-rather-than-war framing creates a template future leaders will employ for other operations. The pattern is clear enough that you can sketch out how it would work:

First, frame things as sanctions enforcement rather than armed force. Instead of “bombing Iranian nuclear facilities,” call it “enforcement of international sanctions on Iranian nuclear development.” Instead of “naval force against North Korean shipping,” call it “maritime interdiction of sanctioned vessels.”

Second, use selective application of force to avoid the blockade designation. Rather than announcing a full blockade, conduct selective seizures and strikes against vessels carrying particular cargo or transporting particular entities. The selective nature supposedly distinguishes it from a wartime blockade.

Third, invoke counterterrorism or counternarcotics authorities to justify operations. Future leaders could invoke similar frameworks—counterterrorism, criminal justice operations, protection of nationals.

Fourth, provide political assurances about not escalating to certain forms of force (ground troops, major campaigns) while maintaining discretion over other forms (airstrikes, naval seizures, special operations). The Rubio assurances created a narrow constraint while leaving extensive room for escalation through air power and naval force.

If this framework successfully allows sustained force lacking War Powers Resolution requirements, the practical effect is to eliminate war authority for the types of force most common in the modern era—airstrikes, naval seizures, special operations forces. Authority would be preserved only for large-scale ground invasions that modern strategic doctrine views as inadvisable anyway. That would effectively invert the War Powers Resolution’s intent, rendering it applicable primarily to the types of force least likely to be attempted.

The Monroe Doctrine as Military Strategy

Trump’s invocation of the Monroe Doctrine adds ideological context to the legal questions. Trump declared that “American dominance in the western hemisphere will never be questioned again,” styling his approach as the “Donroe Doctrine” and suggesting the U.S. was reasserting control over the region through armed means.

The original 1823 Monroe Doctrine sought to prevent European intervention in the Western Hemisphere while purporting to respect the sovereignty of American nations. Theodore Roosevelt transformed it with the Roosevelt Corollary, asserting U.S. right to exercise “international police power” to curb “chronic wrongdoing” in other nations. This expanded interpretation justified U.S. intervention throughout Latin America during the early 20th century—in the Dominican Republic, Nicaragua, Haiti, and elsewhere.

The operations represent a contemporary application of this framework. Rather than merely opposing European intervention, the Trump team asserted unilateral American authority to depose government leaders, conduct armed operations within sovereign nations, control natural resources, and restructure political systems in the Western Hemisphere. Trump explicitly discussed American oil companies investing billions to repair infrastructure. He suggested the U.S. might occupy the country for an extended period. He indicated that economic benefits from oil sales would accrue to “the United States of America in the form of reimbursement for the damages caused us by that country.”

This framework suggests the blockade isn’t merely a sanctions enforcement mechanism or counternarcotics effort, but the armed expression of a doctrine asserting hemispheric dominance. The legal characterization—as sanctions enforcement rather than war, as law enforcement rather than armed force, as quarantine rather than blockade—provides legal cover for operations whose ultimate purpose is political and economic control of a hemisphere through force.

The Unresolved Constitutional Question

Recent debates didn’t resolve the tension between presidential authority and war powers. They highlighted how the legal framework established by the War Powers Resolution has failed to adapt to modern force conducted across a spectrum between formal war and coercive non-armed measures. The blockade of oil tankers, combined with airstrikes and special operations forces, occupies a gray zone the Resolution’s language doesn’t adequately address.

Fifty years after Congress sought to constrain presidential authority, the executive branch has successfully maneuvered to a position where sustained force can continue despite skepticism, because those operations don’t technically constitute “hostilities” in the sense meant by the Constitution. The narrowness of recent votes suggests genuine tension remains within Congress about presidential authority. But the outcomes demonstrated that presidential pressure, careful legal framing, and political negotiation can overcome even bipartisan skepticism.

The blockade continues. Strikes against vessels continue. The Caribbean operations persist lacking formal approval or war declaration. The War Powers Resolution, intended to constrain presidential authority, has been maneuvered around through the legal distinction between blockade and war.

Until Congress revisits the War Powers Resolution with language addressing the ambiguities exposed by blockade operations, selective strikes, and efforts framed as law enforcement or sanctions enforcement, presidential authority over armed decisions will continue to expand within the gaps left by a statute designed for a different era. The next leader—whoever that is, from whichever party—will have the playbook ready to use.

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