The United States has taken an unprecedented step in its Syrian engagement to date by launching missile strikes on the Shayrat military airbase. The US believes this facility was used to stage airstrikes on the town of Khan Shaykhun in Syria’s Idlib province, which used chemical weapons against civilian targets earlier this week. While details about the Khan Shaykhun attack are still emerging, the World Health Organization has confirmed that at least 70 persons—including 21 children—have died of “exposure to highly toxic chemicals.” In the meantime, the US reaction has added to the murky debate over the limited ability of international law and institutions to respond to such acts committed by states inside their borders.

The Khan Shaykhun attacks were believed to have involved sarin gas, a nerve agent that was also used in the 2013 attack on the Damascus suburb of Ghouta. The Ghouta attack had prompted then-US President Barack Obama to consider airstrikes or other military action against facilities controlled by Bashar al-Assad in Syria; ultimately, however, a compromise was reached wherein the Assad regime agreed to surrender its chemical weapons stockpiles for inspection and removal by the Organisation for the Prohibition of Chemical Weapons (OPCW). The OPCW-UN Joint Mission in Syria has subsequently confirmed the inspection and destruction of 96% of stockpiles and production facilities declared by the Syrian government.

As High Representative for Disarmament Affairs Kim Won-Soo reminded an emergency session of the UN Security Council on Wednesday, however, there were a number of outstanding issues related to that initial declaration. The OPCW continues to operate a fact-finding mission in Syria, which investigates allegations of use of chemical weapons; where the mission finds proof that such chemicals were used, a Security Council-mandated Joint Investigative Mechanism (JIM) then tries to identify the perpetrators of such attacks.

At Wednesday’s meeting, members of the Security Council repeatedly cited these two mechanisms as a first-line response to the attacks in Khan Shaykhun. Certainly, determination of facts on the ground is a logical first step, and a largely uncontroversial measure. Yet it raises a larger question: Will those responsible for such attacks be held accountable for their crimes? Recent history in Syria and beyond offers little grounds for optimism in the short to medium term.

The JIM, for instance, has identified specific units of the Syrian Armed Forces as responsible for the use of chemical weapons in Kafr Zita (April 18, 2014), Qmenas (March 16, 2015) and Binnish (March 24, 2015); it has also attributed one attack (Marea, August 21, 2015) to Daesh (also known as the Islamic State). These determinations are based, in part, on the technology and weapons systems involved: Only the Syrian regime has an air force or helicopters, as well as the specific rockets/munitions used in these attacks.

The Security Council had reaffirmed that it would respond to any violations the JIM identified by imposing “measures under Chapter VII of the United Nations Charter,” which encompasses coercive measures such as sanctions, blockades, and enforcement actions. As yet, Syrian authorities have taken no action to investigate or prosecute the military units identified by the JIM, nor has the Council imposed any measures in response to this inaction. These units are not stationed at Shayrat airbase, and the US attack there was a unilateral decision, taken without Council authorization, citing the narrow and debatable basis of national security interest in preventing the use or proliferation of chemical weapons. This is not the kind of concerted international action a reference to Chapter VII would suggest.

As recently as Wednesday, the Syrian UN representative rejected the JIM’s findings in his statement to the Security Council, claiming that the Syrian government does not possess chemical weapons in any form: “We have never used them and we will never use them,” he said. (Syria condemned the US missile strike on Shayrat as “blatant aggression,” while Russia denounced it as “aggression against a sovereign state in violation of international law.”) Syria is also not a signatory to the International Criminal Court (ICC), which would otherwise be entitled to investigate and prosecute war crimes or crimes against humanity committed there, although measures are being taken to document and preserve evidence for use in future accountability or transitional justice mechanisms.

In Syria, the UN is confronted with an uncooperative head of state, bolstered by the support of veto-wielding members of the Security Council. In the face of Assad’s intransigence, every UN effort has floundered, whether it is to negotiate a political solution, to bring about ceasefires or cessations of hostility, to protect civilians or provide humanitarian assistance to besieged cities, and indeed even to prevent the use of chemical weapons or ensure accountability for any of these atrocities.

It is tempting to blame these failures solely on Assad and his Russian and Chinese supporters in the Security Council. Yet that explanation is inadequate: The veto may explain why no robust action has been taken in Syria—except against Daesh, where the interests of the permanent members and regional powers coincide—but it cannot explain why so many states continue to accord the Assad regime a presumption of legitimacy, notwithstanding its extensively documented history of repression. Nor can it explain why the same presumption was extended to others who used proscribed weapons against their own people.

Saddam Hussein notoriously caused over 3,000 deaths (and years of lingering effects, such as birth defects) at Halabja in 1988, yet remained the internationally recognized president of Iraq until his ouster by US forces in 2003. While the legality of the US invasion of Iraq is still a subject of debate, Saddam’s expulsion of UN and OPCW weapons inspectors in October 1998 was seen as a legitimate exercise of sovereign prerogative. Muammar Gaddafi allegedly used toxic gas at the Libya/Chad border in 1987; the attack was poorly planned, and prevailing winds blew the gas back onto his own forces. Chadian forces even captured unused chemical munitions, yet the incident was not even subject to any serious investigation. Gaddafi, like Hussein, remained head of state for decades after.

Why do those who commit such grave violations continue to enjoy formal status and impunity? The more complete explanation is that the UN is an organization of sovereign states, who are understandably hesitant to endorse any dilution in their right to independence from outside intervention.

Assad maintains that protests or conflict in Syria are domestic matters; how his regime responds to them is thus—in the language of the UN Charter—a matter that is “essentially within the domestic jurisdiction” of Syria, in which the UN cannot intervene. This claim would not hinder action mandated by the Security Council under Chapter VII of the Charter, but that would require Russian and Chinese acquiescence. Thus, the only remaining basis on which international action in Syria could even be contemplated is if sovereignty were deemed to be compromised by non-compliance with international norms—e.g. chemical weapons attacks, or arbitrary detention and torture. Previous attempts to suggest such a link, such as the “responsibility to protect” doctrine, proved to be too controversial for most states; at any rate, the Security Council seems unlikely to authorize military intervention on that basis in the near future. And intervention without such authorization—of the kind the US has just undertaken—is, as former US State Department legal scholar Ashley Deeks argues, “very difficult to defend as consistent with international law.”

In codifying the “sovereign equality of all its members,” the UN Charter created a system where any dilution of the norm of sovereignty theoretically affects all states. Such dilution is an unacceptable outcome for regimes who wish to preserve an untrammeled freedom of action within their own territory and they have remained vigilant against any such encroachments. By asserting its sovereignty, a state can thus resort to any number of means to prevent the UN from meaningfully addressing any conflict within its territory—even where the conflict involves illegal and proscribed forms of violence against protected populations, because the violation of those norms has no bearing on the claim of sovereignty. The late South African scholar Leo Kuper once bluntly characterized this claim– “…[The] sovereign state claims, as an integral part of its sovereignty, the right to […] engage in genocidal massacres against people under its rule, and [the UN], for all practical purposes, defends this right.”

That is, perhaps, an overstatement. The evolving direction of international law over the past century has been towards a strong norm of civilian immunity, and few states would explicitly claim a “right to massacre.” Recent developments, such as the trials of former Chadian dictator Hissène Habré and Guatemala’s Jose Efrain Rios Montt, also offer reason to hope that those responsible for atrocities against their own people will eventually be held to account. Unfortunately, it seems clear that the specter of future prosecution is insufficient to deter the targeting of civilians in Syria today; whether unilateral action by the US can create such deterrence remains to be seen.

Ameya Naik works with the Center for Peace Operations at the International Peace Institute. @kianayema