The Legal Case for the U.S. Strike on Syria

On January 10, 2026, the United States and allied forces launched large-scale airstrikes against Islamic State targets across Syria. The strikes, announced by U.S. Central Command as part of Operation Hawkeye Strike, were framed as a direct response to a December attack that killed two U.S. soldiers and a U.S. civilian interpreter.

From a military standpoint, the operation was unsurprising and expected. From a legal perspective, it is more complex—but increasingly common in modern times.

The Syria strikes sit at the intersection of domestic control, international law, and modern counterterrorism strategy. Understanding whether they were lawful requires separating rampant political controversy from the core legal frameworks that actually govern the use of force.

What happened

According to U.S. military statements, the January 10 strikes targeted Islamic State infrastructure and personnel throughout Syria. The Pentagon described the operation as defensive, aimed at degrading ISIS’s ability to conduct further attacks against American interests.

The initial ISIS attack was notable for two reasons. First, it resulted in the deaths of American personnel, including a civilian interpreter. Second, it occurred after the collapse of President al-Assad’s government in late 2024, marking the first such incident in Syria’s post-Assad period.

U.S. forces in Syria are deployed as part of Operation Inherent Resolve, the international effort to defeat ISIS, which once controlled large portions of Syrian and Iraqi territory. Although the group has been territorially defeated, it maintains an active presence, particularly in Syria’s desert regions.

The international law framework

Under international law, all points to the United Nations Charter.

Article 2(4) prohibits states from using force inside another country. There are only two widely accepted exceptions: authorization by the UN Security Council or the inherent right of self-defense under Article 51.

The U.S. did not seek new Security Council authorization for the Syria strikes. Instead, the operation rests on a self-defense justification against a terrorist organization that is looked down upon by the world.

Self-defense after a foriegn attack

Article 51 allows states to use force in self-defense if an “armed attack” occurs. Over the past two decades, the U.S. and many of its allies have interpreted this right to extend to attacks carried out by non-state actors, including terrorist organizations.

In this case, the December 13 attack in Palmyra, carried out by an ISIS gunman and resulting in multiple American deaths, meets the threshold of an armed attack under most common legal interpretations. That makes the American response one protected under self-defense.

The key legal requirement, however, is that any responsive force must be necessary and proportionate, and aimed at preventing further attacks—not simply punishing past ones. Without this requirement, countries could be leveled entirely over minor disputes.

This explains the Pentagon’s careful framing. Officials described the January strikes as targeting ISIS’s operational capacity across Syria, rather than as retaliation. Legally, that distinction matters.

The role of Syrian consent

One of the most contested issues in prior U.S. operations in Syria was sovereignty. Under Assad, the U.S. did not operate with the Syrian government’s consent, forcing the U.S. to rely on more controversial, yet practical, legal theories.

The January 2026 strikes occurred in a different context. Assad was overthrown in December 2024, and reporting suggests the post-Assad government has been more cooperative with U.S. and coalition counter-ISIS efforts.

If Syria consented to the strikes, the sovereignty issue would be resolved mainly under international law. Consent removes the prohibition on using force within another state’s territory.

The extent and form of that consent have not been publicly detailed, which is common in military operations. But even limited cooperation strengthens the legal basis of the operation.

Retaliation versus prevention

International law draws a sharp line between lawful self-defense and unlawful armed retaliation. States may not use force simply to punish an attacker after the fact.

The legality of the Syria strikes, therefore, depends on whether they were genuinely aimed at preventing future ISIS attacks. U.S. statements emphasize precisely that point, describing the operation as necessary to protect U.S. and partner forces and disrupt ISIS activity.

Whether that assessment is correct is ultimately a factual question, but the legal framework itself is clear: prevention is lawful, punishment is not.

U.S. domestic authority

Separate from international law is the question of U.S. domestic legality.

Presidents have long relied on a combination of Article II commander-in-chief powers and the 2001 Authorization for Use of Military Force to conduct counterterrorism operations abroad. Although ISIS did not exist in 2001, successive administrations have treated it as an associated force for legal purposes.

In addition, when U.S. forces are attacked, the executive branch has broad authority to act defensively to protect American personnel. War Powers reporting requirements apply, but they do not require advance congressional approval for immediate defensive actions.

As a result, the domestic legal footing for the Syria strikes is relatively firm, even as debate over the continued use of post-9/11 authorizations persists.

The legal ground

The January 10, 2026, strikes in Syria are likely lawful under the U.S. government’s interpretation of both international and domestic law.

Internationally, the Palmyra attack provides a self-defense trigger, and any Syrian consent further strengthens the case. Domestically, longstanding counterterrorism authorities and force-protection rationales apply.

That does not mean the operation is free from controversy, nor does it settle broader debates about the scope of modern counterterrorism. But as a matter of black-letter legality, the Syria strike fits squarely within the framework the United States has relied on for years.

For now, the operation reflects continuity more than departure—another example of how counterterrorism law functions in practice, even as its boundaries remain contested.