If there is one issue that has sown confusion into the commentary about President Trump’s missile strikes off the coasts of South and Central America, it is terrorism. I’m going to try to clarify that confusion.

Because I want to take head-on the central complication — namely, the question of what legal authority, if any, the status of “terrorist” gives a president to use military force — I am not going to get diverted by the more rudimentary problems that narcotics trafficking is not terrorist activity, and therefore that the Trump administration’s designation of Latin American drug cartels as foreign terrorist organizations (FTOs) is untenable. (I’ve discussed these issues a number of times, see, e.g., here and here). For today’s purposes, I am assuming for argument’s sake that the FTO designations are legitimate.

With those matters off the table, let’s talk terrorism and use of force.

What Matters Is the Existence of an Armed Conflict, Not Terrorist Status

If you take away nothing else from what I’m about to say, take this one thing: The president of the United States has no unilateral authority to use military force in the absence of a legitimate armed conflict. By that, I mean that our nation or its vital interests have been militarily attacked or confronted by the clear and present threat of military attack. There are some nuances when it comes to determining whether the U.S. is truly in an armed conflict. But at bottom, if there is no armed conflict, then there is no presidential authority to use military force, full stop.

That’s the premise. Now, rather than state another abstract principle, let’s cut to the chase on how the premise works vis-à-vis terrorists.

If there is a legitimate armed conflict against terrorists, then (a) the laws of war apply, (b) the terrorists in that conflict are deemed enemy combatants, and (c) our forces may kill them or capture them wherever we encounter them. But understand: What allows our forces to kill or capture under the laws of war is the armed conflict, not the combatants’ status as terrorists.

If there is no armed conflict (i.e., no war or state of hostilities short of war, no military attacks or threat of military attacks), then the president has no authority to use lethal force against suspected terrorists.

In making that assertion, which should be common sense, I am not saying the president lacks authority to take meaningful action against suspected terrorists in peacetime. There are extensive counterterrorism laws in the federal code. If there is sufficient evidence, terrorists can be prosecuted. If there is not yet sufficient evidence, ordinary criminal procedures — grand jury, wiretaps, search warrants, arrest warrants, other investigative techniques — are available to build a prosecutable case against suspected terrorists.

If we think about it, we realize that in peacetime, government agents may not just walk up to a suspected terrorist on the street in New York or London or Karachi and shoot him dead. In peacetime, due process rules and law enforcement protocols are binding on the government. No matter how abominable we may believe a terrorist to be, the executive branch must honor those standards.

As a federal prosecutor in 1995, I spent ten months in a courtroom with the Blind Sheikh (Omar Abdel Rahman), who had approved the 1993 World Trade Center bombing and urged the bombings of American military installations; he had relocated in America only after approving the jihadist murder of Egyptian President Anwar Sadat, and while living in America, he schemed to murder Egyptian President Hosni Mubarak. Now, let’s say that instead of pushing ahead with the trial, my executive branch chain of command had decided, “The hell with this due process twaddle,” and I thus walked into the courtroom and shot him. That would not have been “neutralizing an alien enemy combatant” or some such wartime euphemism. It would have been a murder.

It would have made no difference that there was persuasive force to my contentions that it was suicidal for the United States to be providing discovery from government intelligence files to terrorists who were trying to mass-murder Americans (which I still believe). Nor would it have made a difference that I was aware, in dealing with a jihadist leader capable of commanding terrorist attacks, that nothing other than killing him would stop him (and sure enough, after we convicted the Blind Sheikh, Osama bin Laden credited him with issuing the fatwa approving al-Qaeda’s 9/11 atrocities — which he did from a U.S. penitentiary where he was serving his life sentence).

Those things would have made no difference because, in 1995, the United States was not engaged in an armed conflict (even if jihadists considered themselves to be in an armed conflict with the U.S.). Hence, civilian due process applied, not the laws of war.

It was irrelevant that the Blind Sheikh was a globally renowned terrorist. What mattered was that there was no armed conflict, so he was a defendant, not an enemy combatant. The fact that he was a terrorist conferred no authorization to use military force. Criminal prosecution was the only game in town.

Who Decides Whether the United States Is in an Armed Conflict?

The main confusion here stems from the facts that (a) the president does have limited constitutional authority to use military force without congressional authorization, and (b) in modern times, that authority is often triggered by terrorist activity.

From these premises, many have understandably leapt to the conclusion that the president must, in all circumstances, have constitutional authority to use military force against terrorists. Certainly, that’s what President Trump thinks. But that conclusion is simply wrong. Of course, there are complications and gray areas, which can easily confound people who are not steeped in the germane legal principles. But let’s again start with the basics.

The Constitution vests the power to declare war (and its lesser-included power to authorize military force) in Congress. It also gives Congress the powers to provide, maintain, and regulate the armed forces. And significantly when it comes to current government operations in the Caribbean, Congress is also endowed with the power to define and punish felonies committed on the high seas.

The war power is vital. It enables Congress to declare a state of hostilities and specify the regime or foreign entity that is the enemy. This triggers application of the laws of war, establishes the legal status of combatants, and empowers the president to take actions that are only permissible in wartime (e.g., to detain and deport nationals of the enemy state).

The Constitution makes the president the commander in chief. His principal war power is to prosecute the use of force as Congress has authorized it, not to authorize it himself.

Life is complicated, so this default setting is not always practical — especially as weapons technology has evolved, making it possible to project ever greater force in increasingly less time. Consequently, if the United States is forcibly attacked or is under an authentic threat of forcible attack, the president may unleash military force to quell the attack or threat, even if Congress has not authorized military force. And this is not optional: In the Civil War–era Prize Cases, the Supreme Court reasoned that the president has not merely the power but the duty to marshal whatever force is necessary to protect the nation from such attacks and threats of attack.

I mentioned complications and gray areas. They are unavoidable due to the elusive nature of threats, the realities of politics, and the bedrock constitutional separation-of-powers principle.

A president may believe an inchoate threat is more real and imminent than it objectively appears to be — and, we must bear in mind, the president has access to executive intelligence files that others do not. In the modern era of progressive governance and media focus on the president, Congress has become passive, with lawmakers seeking to avoid accountability — content to watch as the president makes major national security decisions, then bask in the glow of success or pounce on failure along partisan lines. And the decision whether to use military force is a political one that, in a free republic, should be made by officials accountable to the American people whose lives are at stake; ergo, the courts — lacking institutional competence and political accountability — generally won’t intervene in matters involving the use of force against those the political branches determine are foreign enemies.

When all the system’s players act in good faith, these complexities are tolerable. A president will not use force unilaterally unless there is a true military threat; Congress will be supportive of a president who has carefully weighed the pros and cons; and the courts will butt out.

On the other hand, a willful president may concoct a crisis when there is no threat (in particular, no military threat); Congress may find it difficult to mobilize opposition because lawmakers from the president’s party are pressured into supporting him; and the courts will then be beckoned to act because, even though the president’s national-security determinations are entitled to deference, there is a patent gulf between objective reality (no apparent forcible threat) and the statutory triggers for presidential action (determination that a forcible threat exists).

There can thus be a stark difference between what the Constitution dictates and what government officials actually do. That mismatch signals abuse of power. Yet, because courts won’t get involved in the political realm — the decision to use miliary force — executive overreach can be reined in only by Congress. Its constitutional arsenal runs the gamut from oversight hearings and political pressure, to cutting off funds, to impeachment. But these remedies are not on autopilot; Congress has to decide to use them.

So here is the bottom line: A president may properly employ military force without congressional authorization only if there is a true military threat to vital American interests. But if the president ignores that limitation, no one can stop him from unleashing military force — the commander in chief has that raw power, even if he lacks the constitutional authority. And if Congress lacks the will to use its powers to make such a president desist, the president can persist in using force, even if it is constitutionally improper for him to do so. In our system, the question of “who decides?” is often more consequential than the question of “what is the objectively proper decision?”

How Do Terrorists Fit In?

You may have noticed that I barely used the word terrorist in forging through that last section on legitimate uses of force. That, again, is because the dispositive issue is whether there is a true forcible threat to vital American interests, not whether a person or entity suspected of being a threat happens to be engaged in terrorist activity.

A concrete example. On August 7, 1998, al-Qaeda bombed the American embassies in Kenya and Tanzania, killing 224 people. Less than two weeks later, on August 20, President Clinton authorized missile strikes against what our intelligence agencies assessed were al-Qaeda training camps in Afghanistan and a suspected al-Qaeda chemical weapons plant in Sudan.

Clinton could have gone to Congress for authorization, but he reasonably concluded that these targets presented a clear and present threat of more attacks against American facilities. Delay and public hearings would have endangered the country. This was a proper resort to the president’s authority to use force without congressional authorization. But understand: It was proper because of the threat of forcible attack, not because of the happenstance that the threat came from terrorists as opposed to, say, a hostile nation-state.

Another example. On January 3, 2020, President Trump authorized a drone strike that killed Qasem Soleimani, the Iranian commander of the Islamic Revolutionary Guard Corps-Qods Force. Putting aside his long history of coordinating terrorist activity against the United States, Soleimani was then directing Iranian proxies — jihadist militias — that were attacking U.S. and coalition forces in Iraq and Syria.

Delay could have resulted in a missed opportunity to eliminate a key enemy commander and, in turn, more deadly attacks against American forces. Ergo, it was proper for the president to attack Soleimani without congressional authorization.

Was Soleimani a terrorist? Technically, he may have been better understood as a member of the military force of a hostile nation-state who directed the activities of terrorist proxies. Yet, he had been designated as a global terrorist in the Obama era, and the IRGC had been designated as a terrorist organization in the first Trump term. No matter: The use of lethal force against Soleimani was constitutionally legitimate because of the very real threat that he was about to carry our more forcible attacks against Americans, not based on hairsplitting about whether Soleimani was a terrorist rather than a soldier.

Conclusion

President Trump, his administration subordinates, and his supporters continuously claim that the boats our armed forces are attacking off the coasts of South and Central America are attached to foreign terrorist organizations (the cartels) and are therefore constitutionally legitimate targets of military force, despite the absence of congressional authorization. That is wrong.

As a matter of law, the statutory terrorist designation process does not authorize the use of force. Rather, it empowers the executive branch to seize terrorist assets and to prosecute people or entities providing a designated foreign terrorist organization with material support. This is why, following the 9/11 attacks, President Bush sought congressional authorization to use military force against al-Qaeda and its abettors; al-Qaeda had been designated as a foreign terrorist organization two years earlier, but that designation — al-Qaeda’s mere status as a terrorist organization — did not authorize the use of force.

What empowers a president to use force, whether against foreign terrorist organizations or foreign countries, is the existence of a clear and present threat of forcible attack against the United States and its vital interests — an armed conflict. The importation of illegal narcotics is not a threat of forcible attack at all, much less a clear and present one. Congress — which, as noted above, has constitutional authority to define and punish felonies on the high seas — has made narcotics trafficking, including importation, a crime. Congress has not deemed it an act of war.

And that, at last, is a salient point. With its constitutional war power, Congress could permissibly declare war or authorize military force against drug cartels. While I doubt that I could be persuaded to see drug shipments as analogous to forcible attacks, Congress could, in its discretion, conclude that, at certain mass quantities, the importation of illegal drugs is effectively similar to forcible attacks, such that it should be treated as hostile activity worthy of a military response. In our system, though, that is for Congress to decide. For now, Congress has extensively regulated illegal drug importation as a crime.

The president lacks Congress’s power to authorize war and to legislate. The president’s unilateral power to use military force is limited to responding to military attacks or threats of military attacks. That power does not hinge on whether those attacks or threats come from terrorists. Narcotics trafficking — regardless of whether the traffickers are deemed terrorists — is not a threat of military attack.