When President Biden ordered an airstrike on Iranian-supported militia groups in Syria, his actions rekindled long-standing debates about the legality of U.S. military intervention in that country under the Constitution and the 1973 War Powers Act. Similar debates arose after Donald Trump ordered strikes in Syria in 2017 and 2018 — although those targeted Syrian government facilities associated with chemical weapons.

Critics have argued that both Trump’s and Biden’s strikes were illegal under the Constitution because they were not approved by Congress. “The president should not be taking these actions without seeking explicit authorization,” said Rep. Ro Khanna (D-Calif.) this month. In my view, that is incorrect: Advance congressional authorization is not required for small-scale actions taken in self-defense against adversaries that have attacked U.S. forces — as Iranian-backed militias did in the most recent case.

But the debate over these strikes, taken in isolation, obscures a larger question: While the recent action may pass constitutional muster, the overall legality of the long-standing U.S. military presence in Syria is profoundly questionable; it almost certainly requires congressional authorization. Barack Obama, Trump and now Biden all deserve blame for failing to secure it throughout almost seven years of military operations.

Under the Constitution, whether the strikes are legal hinges on whether they amount to the initiation of “war.” (There is a separate, equally heated argument over whether the strikes violated the U.N. Charter, but my focus here is U.S. law.) The boundary between “war” and a smaller-scale military strike that the president can order on his own is admittedly fuzzy. But both the Trump and Biden strikes were of extremely limited scope and duration. The self-defense aspect of the Biden strikes makes last month’s case even clearer: Congressional authorization isn’t required when hostilities have been initiated by the enemy.

But such rationales cannot justify the overall U.S. military presence in Syria. During the past seven years, U.S. forces — including both air power and ground troops — have been regularly engaged in combat against ISIS and other groups in Syria, while also providing logistical support to rebels fighting the regime of Bashar Assad. U.S. ground forces reached a peak of some 2000 in 2017, and some 600 to 900 remain to this day, despite a partial withdrawal under the Trump administration. The United States and its allies have also launched thousands of air and missile strikes in the country. The continuing U.S. intervention against the ISIS terrorist group — the main original goal of our military presence in that country — is clearly large enough to qualify as a war, in the constitutional sense.

Ever since conflict with ISIS began under Obama in 2014, successive presidents have offered specious rationales claiming that congressional authorization already existed. At various times, Obama administration officials claimed authorization under the 2001 Authorization for the Use of Military Force targeting the perpetrators of the Sept. 11, 2001, attacks on the United States, or the 2002 AUMF against Saddam Hussein’s regime in Iraq. The Trump administration also cited the 2001 AUMF as authorization for its operations in Syria. Both arguments are highly dubious, as the adversaries we face in Syria are clearly distinct from both the al-Qaeda perpetrators of the 9/11 attack (with which ISIS has been in conflict for years), and Saddam Hussein’s long-defunct government.

In addition to violating the Constitution, the Syria intervention — viewed as a whole — also runs afoul of the 1973 War Powers Act, which requires the president to get congressional authorization for any deployment of military forces in “hostilities” abroad within 90 days of their commencement. It is undeniable that the U.S. intervention in Syria involves the kind of “hostilities” covered by the Act. Where Syria is concerned, the War Powers Act deadline passed a long, long time ago — during the Obama administration.

To its credit, the Biden administration has not attempted to stretch previous AUMFs to justify its recent airstrike. Instead, the president cited his inherent power, as commander in chief, to defend U.S. troops against attack. This is a strong rationale for the limited airstrike conducted on Feb. 25, but cannot justify the broader U.S. operations.

The requirement of congressional authorization for initiating war is backed by the text and original meaning of the Constitution. Article I gives Congress the sole power to “To declare War.” As James Madison put it, “[t]he constitution supposes, what the History of all Gove[rmen]ts demonstrates, that the Ex[ecutive] is the branch of power most interested in war, & most prone to it. It has accordingly with studied care, vested the question of war in the Legisl[ature].” Their greatest concern was ensuring that no one person would have the power to take the nation to war. This is an even more serious danger in an era when the Oval Office can be occupied by an impulsive demagogue ignorant of international affairs.

There are also strong “living constitution” considerations supporting the requirement of congressional authorization. Unlike in the 18th century, an era of sailing ships and horse-drawn carriages, Congress can convene very quickly for a vote to authorize military action. That obviates the principal reason for giving the executive greater discretion over war initiation — the notion that he alone can act swiftly, when necessary.

The constitutional requirement of congressional authorization is more than just a legal technicality. Not only does it prevent dubious conflicts begun at the behest of a single man; it also increases the chances of success if we do enter a conflict. If the president is required to get congressional authorization for war, he will be forced to build up a broad political consensus behind his decision; that increases the likelihood that we will stay the course until victory is achieved, as opposed to bailing out when difficulties arise.

If such a consensus is absent, it is usually best to avoid the conflict entirely. The failure of Obama’s 2011 military intervention in Libya, — he called the lack of planning for the aftermath of that conflict his “worst mistake” as president — was partly caused by his decision to forgo building the necessary political consensus for congressional authorization.

Although U.S. airstrikes against Libya lasted for some seven months, and helped bring about the overthrow of the regime of Libyan dictator Moammar Gaddafi, the Obama administration claimed there was no need for congressional authorization for its actions, on the dubious ground that it did not involve a genuine war, or even “armed hostilities” under the War Powers Act. Subsequently, the country descended into chaos and ISIS-aligned groups and other dangerous organizations took over substantial parts of its territory; the United States largely walked away.

There was good reason to take military action against ISIS, and (more debatable) against the oppressive Assad regime and Iranian proxies in Syria. But for both legal and pragmatic reasons, it is important to ensure that large-scale military interventions have congressional authorization.

The Biden administration indicated last week that it wants to work with Congress to replace the outdated 2001 and 2002 AUMFs with “a narrow and specific framework that will ensure we can protect Americans from terrorist threats while ending the forever wars.” At the same time, some members of Congress from both parties have expressed interest in reasserting congressional control over war authorization. Whether these efforts pan out remains to be seen; the failure of previous attempts provides reason for skepticism. But there is at least a chance that Biden and Congress might — at long last — end the era of unauthorized executive warmaking.