The United Nations Charter, to which all member states are signatories and which prevails over all other treaties and agreements, states that the organization is obligated to “determine the existence of any threat to the peace, breach of the peace, or act of aggression” and to take military and nonmilitary action to “restore international peace and security.”
The justices at the Nuremberg trials in 1946 concluded that “to initiate a war of aggression … is not only an international crime; it is the supreme international crime differing only from other war crimes in that it contains within itself the accumulated evil of the whole.” 
The U.S. Constitution’s Article I states that only Congress has the authority to declare war, with the understanding that, per Article II, the president is empowered to respond to a “sudden” or imminent threat only if there is no time to pass such a declaration. An Authorization for Use of Military Force (AUMF) amended in 2016 grants the president blanket authority to respond militarily to threats against the United States, but only if they originated with al-Qaeda and “associated forces.”
So how is it that on April 6 the United States attacked a fellow member state in the United Nations that has an internationally recognized sovereign government? That member state posed no imminent threat, had not attacked the United States, and was not at war with Washington. Nor did that member state consist of or support al-Qaeda or an associated group, and it was not under sanction from the United Nations Security Council to authorize any other member state to act against it. On the contrary, that member state was actively fighting several terrorist groups as defined by the U.S. government that had occupied its sovereign territory.
I am, of course, referring to the cruise-missile attack on Syria, which many critics are belatedly recognizing to be illegal under both international and U.S. law. But illegality being related to the ability to enforce the law, there has been little apparent desire on the part of the United Nations to bring Washington to heel, and the U.S. would surely use its Security Council veto to stop any undesirable UN action.
The United States has been backing various schemes to undermine and force “regime change” on Baathist rule in Syria since 2006, well before the so-called Arab Spring brought protests to the streets of Damascus. More recently, Washington has been arming and training so-called rebels against the Bashar al-Assad regime, ostensibly in unrealistic hopes that some kind of transition to a moderate, pro-Western regime might take place. Current White House policy appears to consist of putting pressure on ISIS and al-Qaeda-linked al-Ansar, which the Syrian government is fighting, while also demanding the replacement of Assad to permit resumption of all-party peace talks. Apart from those general markers, there has been little attention paid to what might happen on day two, after Assad is gone. Reasonable concerns that the vacuum created might be filled by radical Islamists have largely been ignored.
But even if the United States policy is a muddle, there are others in the region who know what they want and are pretty sure what they have to do to get there. Saudi Arabia and Qatar also have been fighting an unsanctioned and illegal war against Syria with very little in the way of pushback from the international community. They have been hostile to Syria’s government for two decades and began bankrolling and arming dissidents inside the country after fighting began in 2011. Their reasoning is that Syria has become an ally of Iran and Lebanese Shi’ites, including Hezbollah, threatening to create a ring of Shi’ite-dominated territories that will cut across the middle of the Arab Middle East and empower the government in Tehran, which the Saudis in particular see as their regional enemy. It is also possible that the Saudi export of militant Wahhabism also plays a role; Syria, which like Iraq before it is tolerant of most religions, is often accused of being both unacceptably secular and supportive of heretics.
So the Saudis would like to see a Syria in which the Sunni Arabs are dominant, which will presumably lead to discrimination against Shi’ites, Alawites, and Christians—as well as a severing of political ties with Iran. In reality, a broken Syria would likely turn out much like neighboring Iraq, with minorities in trouble and a lack of effective central control. But that would be all right with Riyadh, as it would mean the alliance with Iran would be de facto dissolved. Whether the Syrians would benefit from the change is immaterial as perceived through the optic of Saudi interests.
Turkey would also like to see Assad gone and a Syria in chaos. On April 25, Ankara attacked Kurdish targets in both Syria and Iraq, including members of the YPG militia, who are U.S.-trained and -supplied allies against ISIS. Twenty YPG militiamen were reported killed. The Turks claim that virtually all armed Kurdish groups are terrorists, allied with Turkey’s domestic terrorism problem, the Kurdish Workers Party (PKK). Turkey particularly fears that Syria will permit the creation of a Kurdish-dominated entity along their mutual long and difficult-to-defend border. It wants Assad out because it has accused him, perhaps rightly, of supporting the incursions of Kurdish terrorists, but it chooses to ignore the fact that the current problems with the Kurds were in part initiated by the government of then-Prime Minister Recep Tayyip Erdogan. The Turkish leader needed a credible enemy for internal political reasons, to discredit a largely Kurdish party that opposed him. 
Turkey has supported ISIS in the past, including treating their wounded in Turkish hospitals and allowing them to regroup in safe havens inside Turkey, mostly because the terrorist group is a foe of the Kurds. It has also been plausibly claimedthat Ankara supplied the sarin that was used in several attacks on Syrian civilians that have been conveniently blamed on the government in Damascus. The shoot-down of a Russian fighter bomber in December 2015 may have also been a crude attempt to draw the U.S. and NATO into a war against Assad and Moscow. Ironically, playing both sides in an all-too-visible attempt to bring down Assad has destroyed any credibility that Erdogan has. And weakening Syrian central-government control and de facto handing power over to a ragtag of rebels and local tribesmen will virtually guarantee the emergence of a Kurdish statelet, but Ankara is apparently not thinking that far ahead.
Finally, there is Israel. Israel, unlike Syria’s other adversaries, has been seeking to destabilize its neighbor for more than 20 years and has little or nothing to do with either Iran or the Kurds. The Yinon Plan of 1982, drafted when hard-right politician Menachim Begin was prime minister, was outlined in a paper entitled “A Strategy for Israel in the 1980s.” It maintained that Israel’s security would be guaranteed only if its neighbors were to be somehow forced or otherwise induced to come apart and return to their tribal, ethnic, and religious constituencies, which had been arbitrarily combined into individual nation-states by the imperial powers after World War I. The Yinon Plan included recommendations for military action to accomplish what might not be done more clandestinely, including an Israeli invasion of Syria to break the country down into Alawite, Druze, Sunni, and Christian communities. A fragmented Arab world creating a “Balkanized” weak-state system for the region, combined with relocation of the Palestinians to Jordan, would remove all the threats to Israel’s survival.
The Yinon Plan never became official Israeli government policy. But it might be seen as a blueprint for the regional actions subsequently undertaken by Tel Aviv, which have persistently sought to weaken Arab governments perceived as being too powerful or threatening. A second paper, “A Clean Break: A New Strategy for Securing the Realm,” followed in 1996, during the prime ministry of Benjamin Netanyahu. It was authored by a group of American neoconservatives that included Richard Perle, Douglas Feith, Paul Wolfowitz, and Meyran and David Wurmser. It advocated a policy of preemption for Israel and was particularly focused on Iraq and Syria as enemies. Once critic described the document as endorsing “a mini-cold war in the Middle East, advocating the use of proxy armies for regime changes, destabilization and containment.”
More recently, Israeli officials have made clear that they would prefer to have“moderate rebels” in control in Syria than the Assad government. They have reportedly provided medical care for wounded militants, possibly including ISIS. It would appear that there is a de facto truce between the Israeli military and ISIS, as ISIS reportedly apologized when one of its associated groups fired on IDF units in the Golan Heights back in November. 
Israel has carried out a number of air strikes against Syrian bases and military units, most recently a missile attack near Damascus on April 27. There are also reports that it is already using its new U.S.-provided F-35 stealth fighters for combat missions against Syria.
Israel would prefer to have a fragmented political situation across its border rather than a unified and capable government. The former constitutes an easily containable threat, while the latter will no doubt continue efforts to regain most of the Golan Heights, which Israel occupied in 1967 and continues to hold. So the choice for the Israeli government is a simple one—and it does not include whatever the United States might currently be envisioning. It is, in fact, much closer to what Turkey and the Saudis want.
Daniel Larison has frequently warned that the U.S. is encumbered with allies that are allies in name but not in reality. In terms of actual national interests, it should be observed that the Saudis, Qataris, Turks, and Israelis are all currently (or have been recently) in bed with terrorist groups that the United States is pledged to destroy. All of them have either directly attacked or arranged for surrogates to attack the legitimate Syrian government, which is opposing ISIS and al-Ansar on the battlefield. Turkey has also attacked Kurdish militiamen allied with and trained by Washington.
The Trump administration will certainly not pressure Israel to change course when the president travels to Jerusalem later this month. Apart from anything else, Trump will be aware that Republicans in Congress have launched an Israel Victory Caucus and that all 100 senators have recently signed a letter to the United Nations demanding that it abandon its “anti-Israel bias.” So there is no wiggle room there. Nor will The Donald squeeze President Erdogan when he arrives in Washington next week, for fear that the already feckless and foundering Syria policy will become even more unmanageable. And the Saudis are always there in the background, using their money weapon to buy influence and manage the narrative. 
So the answer to the question “Who is destroying Syria?” must be “Pretty much everyone.” Though there are different motives surfacing regularly by the key players to justify the continued carnage. From the commentary coming out of the foreign and defense ministries in Washington, Riyadh, Ankara, and Tel Aviv, it is more than a bit hard to discern if there might be a way out of this quagmire. Otherwise, it appears that it will continue to be business as usual until everyone gets tired, declares victory, and goes home.
Philip Giraldi, a former CIA officer, is executive director of the Council for the National Interest.