Despite his largely symbolic strike on a Syrian airfield in response to the April 4 nerve gas attack by the Assad regime, President Donald Trump has given no serious indication that he wants to make a broader intervention in Syria. As a candidate, and even as a president, Trump has pledged to leave the region to sort out its own troubles, apart from a stepped-up effort to defeat the Islamic State (ISIS). He may quickly learn, though, that one-off military actions driven by domestic politics have a way of turning into something far more substantial.

Already, tensions with Syria’s close ally, Russia, have been escalating, with little sign that the US administration can bring about a change toward Damascus. Bashar al-Assad long ago learned he can operate with impunity. But even larger questions surround another Assad ally, Iran, which, though less conspicuous, has had a crucial part in the changing course of the war and in the overall balance of power in the region. While the Trump administration regards Iran as enemy, it has yet to articulate a clear policy toward it—or even to take account of its growing influence in Iraq and Syria.

If the Syrian leader ignores the warning conveyed by the Tomahawk missile strike, what will be Trump’s next move? Will he be able to resist the temptation to deepen US involvement in Syria to counter a resurgent Iran? How might this affect the battle against the Islamic State—a battle that has already created an intricate power struggle between the many parties hoping to enjoy the spoils?

Consider the array of forces now in play: in Syria, the war on ISIS has been led by Syrian Kurds affiliated with the PKK, the militant Kurdish party in Turkey, which has been in conflict with the Turkish state for the past 33 years—another US ally. In Iraq, there are the peshmerga, the fighters of a rival Kurdish party, who are competing both with the PKK and with Iraqi Shia militias for control over former ISIS territory. There is Turkey, an avowed enemy of Assad that is currently at war with the PKK and its Syrian affiliates, and has moved troops into both northern Syria and northern Iraq in order to thwart the PKK. There is Russia, which, in intervening on behalf of Assad, has created a major shift in the conflict.

And finally, there is Iran, which has made various alliances with Assad, Shia militias, and Kurdish groups in an effort to expand its control of Iraq and, together with Hezbollah, re-establish a dominant position in the Levant. Moreover, Iran has also benefited from another tactical, if unofficial, alliance—with the United States itself, in their efforts to defeat ISIS in neighboring Iraq.

Given all this, the US strike does nothing so much as complicate an already explosive situation. The loudest cheerleader of Trump’s action last week was Israeli Prime Minister Binyamin Netanyahu, who has been especially concerned as Iran and its ally Hezbollah benefit from their tactical military alliance with Russia to prop up the Syrian regime. But whatever advantages some may see in the recent US stand against Assad, it makes it even less likely that a stable postwar order can be achieved.

As my own trip to northern Iraq and northern Syria last month revealed, even as the international coalition makes major gains against the Islamic State, the region’s crises are multiplying. Worse, they are also, increasingly, intersecting, sucking in outside powers with a centripetal force that has proved impossible to withstand.

Four years since its emergence in eastern Syria and subsequent lightning conquest of western Iraq, ISIS is quickly losing ground. After months of encirclement by coalition forces, backed by the airpower of the US, ISIS now finds itself increasingly overwhelmed in Mosul, Iraq’s second-largest city and once one of the group’s strongholds. Its fighters are exhausted, its ranks depleted, but its remaining forces are clearly prepared to fight to the bitter end. The battle for Mosul has caused high casualties on both sides and especially among trapped civilians, including from American bombings in the old city’s dense warren of streets and alleyways. It has also caused extensive destruction, though important infrastructure has mostly been left intact: the power and water supply, as well as the cell phone network, still function. As Iraqi army and elite US-trained counter-terrorism forces push deeper into the old city, they take neighborhoods street by street. Civilians adapt, moving their markets on both sides of the line accordingly as it creeps northward.

It is striking that, throughout the region, both states and non-state groups like ISIS and the Kurds draw on language of encirclement and victimhood in their struggles for power. Perceptions can often count more than reality, leading to tensions and military actions that might otherwise be easily avoided. For example, Saudi Arabia sees a revolutionary and ascendant Iran gaining power and increasingly encircling it, in a region the Saudis thought they dominated—in Syria, Lebanon, Iraq, Bahrain, Yemen, the Red Sea. As a result, Saudi leadership has not only backed various rebel groups fighting the Assad regime, but also launched a war against the Houthis in Yemen—which it regards as proxies of Iran.

For its part, Iran says it is surrounded by pro-American states—including Saudi Arabia and the other Gulf states, Afghanistan, Turkey, and, further afield, Israel—which are intent on keeping it isolated and under sanctions, and preventing it from fulfilling its enormous potential. Meanwhile, it fears being cut off from its ally Hezbollah in Lebanon in a post-Assad Syria.

Mike King

The human cost of these rivalries has been extraordinary. Over 3.3 million people are currently displaced in Iraq, a population that suffers from shortages of food, clothes, shelter, and basic services while contending with a variety of forces hostile to them. In Mosul, another major threat to civilian life is the Mosul dam just upstream on the Tigris, which has been dangerously weakened by structural flaws and years of neglect. It has held while engineers feverishly add grout to all the necessary places. Those with knowledge of the matter anxiously watch the sky, praying for no rain: it takes a damaging drought to prevent a killer flood.

Meanwhile, a new set of conflicts may be about to begin. These are of two kinds. The first kind of conflict is a political and sectarian one. The various forces aligned against ISIS know that they can defeat the group on the battlefield. But they lack the tools to suppress “Daeshism,” the group’s ideology (after Daesh, the way the group is referred to in Arabic), which will remain attractive to Sunni Muslims as long as they feel politically excluded and as long as the various powers in the region continue to exploit sectarian tensions between Sunnis and Shia.

Moreover, since ISIS is in many ways an Iraqi organization—its leader Abu Bakr al-Baghdad is an Iraqi, and a number of its senior commanders (many now dead) served in the Saddam regime’s security services—the challenge of Daeshism will be most acutely felt in Iraq. The problem is all the more intractable given that Shia Islamist parties dominate the government in Baghdad, and the offensive against Mosul was largely spearheaded by Iran-backed Shia militias, notwithstanding the fact that the local population in Mosul and surrounding areas are overwhelmingly Sunni. These militias are more powerful than the army and have become a virtual state within a state.

Already, local ISIS recruits are blending in with civilians who are taking refuge in camps—lying low, waiting for more opportune times. This threat could be addressed, in part, by giving local Sunni populations a say in municipal councils and by giving local and federal forces joint control of security, but few Iraqi politicians in Baghdad have demonstrated either aptitude or appetite for such an inclusive approach. Instead, they and the militias they support (and that effectively control them) seem motivated by revenge, and so the problem of Daeshism will fester. ISIS remnants will continue to create havoc at every opportunity, and one can expect there will be many. This is a challenge in Syria as much as it is in Iraq: many of the people living in areas vacated by ISIS reject the alternative, be it rule by the central government or by Shia or various Kurdish militias. This will enable ISIS fighters, currently hiding out in plain sight, to make a comeback if fighting continues among the various contenders for power.

These local conflicts are cross-cut by the standoff, mainly rhetorical but fought by proxy, and involving nuclear politics, between Israel and Iran. “It’s like a game of Risk,” an academic and political go-between in northern Syria told my colleagues and me last month. To forestall an Israeli attack on its nuclear program or an attempt at regime change in Tehran, Iran has long backed regional proxies that extend its power across the region. Foremost among these is Hezbollah, the Lebanese “Party of God,” which has been an integral part of what Iran calls its “forward defense,” taking the place of missiles that could effectively target Israel, which Tehran still lacks. Through Hezbollah, Iran can use Lebanon as a launching pad within fifty miles of major Israeli cities.

Yet Iran’s strategic posture is only as strong as the supply line that supports it. Until now, this has been an air route connecting Iran to Hezbollah via Iraq and Syria, but the Iranian government wants to consolidate this with a land corridor running from its own borders to the Mediterranean. This is not merely an accusation one hears in Tel Aviv, Ankara, Riyadh, Amman, or Abu Dhabi, but an aim that is acknowledged by Iranian analysts themselves, who describe it as a strategic necessity. It needs these routes to get arms to Hezbollah. That explains the importance of Iran’s alliance with the Assad government in Syria, and also why Iran and Hezbollah were in such a hurry after 2011 to prop up the Syrian regime when it was threatened with imminent collapse. (Iran has also long wanted to diversify its energy export routes, and has mooted plans to construct an east-west pipeline across Iraq to the Syrian coast.)

Two events have enabled the execution of Tehran’s plan: the 2003 US invasion of Iraq and dismantling of the Iraqi army, which swung the balance of power in Baghdad toward Shia Islamist parties susceptible to Iranian influence; and ISIS’s rapid rise to power in 2013 and 2014, in part precipitated by then-Iraqi Prime Minister Nouri al-Maliki’s overt sectarianism and lethal suppression of peaceful Sunni protests. Using Iraqi militias it has recruited and trained since 2003, Iran has piggybacked on the US-supported effort by the Iraqi army and Kurdish Peshmerga to confront ISIS. These militias have rapaciously taken over the Sunni towns they and the army wrested control of from ISIS. Soon they will be able to stretch westward from Mosul toward the Syrian border. Only ISIS holdouts in Mosul and adjacent areas stand in their way; these will soon be gone.

This is particularly unnerving to Iran’s enemies and rivals, and not only Israel. For one thing, the envisioned Iranian land corridor threatens to cut off Iraq’s own north-south oil pipeline. Northern Iraq’s oil, concentrated around the town of Kirkuk, is important to Turkey, which levies transit fees. But Kirkuk oil passed through territory that was seized by ISIS. This left Iraq’s leaders in Baghdad with no alternative other than to divert the flow through a new pipeline crossing the Kurdish region to Turkey. The Iraqi government realized that this would strengthen Kurdish autonomy, but it was a cost they were willing to incur if it meant continued revenue at a time of low oil prices. A disruption of the pipeline by Iran or the PKK would have consequences for Iraqi Kurds, for Turkey, and for European consumers—leverage that could potentially be a strategic asset for Iran in time of war.

Turkey, with which Iran has had a fixed border and stable diplomatic and trading relationship for over five hundred years, also feels threatened because the envisioned Iranian corridor skirts Turkey’s border with both Syria and Iraq. This tension is most visible in Sinjar, a remote but strategically crucial Iraqi district and border town that connects Mosul with Syria. Sinjar was the site of ISIS’s August 2014 genocidal attack on the local Yazidi community; it also has been the focal point, more recently, of the conflict that has emerged between the two main Kurdish groups: the PKK and its Syrian affiliates, on the one hand, and the Kurdistan Democratic Party (KDP), which is allied with Turkey, dominates the Kurdish Regional Government in Iraq (KRG), and has its own fighting forces.

In the 2014 attack, ISIS used a joint force of local and outside fighters to abduct at least five thousand women and girls, and killed an even greater number of men and boys after the precipitous, pre-emptive withdrawal of the KDP peshmerga, who had previously controlled the area. Many Yazidis were rescued—not by the Iraqi army or returning peshmerga, however, but by PKK fighters rushing in from Syria and from their mountain redoubt of Qandil on the Iraq-Iran border, hundreds of miles away. These PKK units shepherded civilians to safety in Syria, who were then resettled in displaced people camps in the Iraqi Kurdish region.

The PKK covets Sinjar because its presence allows it to control part of the Syrian border and smuggle goods to its Syrian affiliate, the Syrian Kurdish PYD, whose four-year-old experiment in self rule has come under increasing threat. After rebranding their units in an attempt to hide their PKK origin, the PKK fighters who had rescued the Yazidis claimed to be a local force and stayed in Sinjar. No independent observer I know has fallen for the ruse; the Turkish government, which is locked in a deadly conflict with the PKK in southeastern Turkey, certainly has not. In recent months, Turkey has taken military action against the PKK’s local affiliates in northern Syria and has imposed an economic blockade on the territory under these groups’ control.

Meanwhile, the Iraqi Kurdish KDP sees the PKK as a foreign intruder in Sinjar, and fears both its fighting prowess and its pan-Kurdish ambitions. (PKK fighters have also deployed in other parts of northern Iraq, including Amedi, Makhmour, and Kirkuk.) In northern Syria, the PKK and its local affiliates seek to connect non-contiguous Kurdish districts while putting pressure on Turkey. Last month, a senior Iraqi Kurdish official told me, “The PKK wants to control the border with Syria and our border with Turkey, from the mountains down into the lowlands, and become leader of all Kurds.”

For Turkey, the PKK’s presence in Sinjar is especially threatening because there the interests of Iran and the PKK coincide. To consolidate its land corridor, Iran needs one other crucial link: the Turkmen town of Tel Afar, which is part-Sunni, part-Shia and is situated directly between Sinjar and Mosul. As part of the fight against ISIS in Mosul, driving up from the south and circumnavigating the city, Iran-backed Shia militias made a beeline for Tel Afar and seized its airport. As of early April, some ISIS fighters remained in the town but their defeat is imminent. Once the Shia militias control Tel Afar, they can connect with the PKK in Sinjar, and Iran will have accomplished much of its goal. Iran in 2011 had forged a tactical alliance with the PKK and its Syrian affiliates. Since then, the PKK has relied on Iranian support in Syria and Iraq in return for agreeing to halt the insurgency, carried out by another affiliate, inside Iran (which is home to a large Kurdish population of its own).

The KDP retains a small military presence on the road from Sinjar to Tel Afar and, backed by Turkey, appears ready to block both Iran and the PKK, and regain ground it lost to the PKK three years ago, especially along the Syrian border. On March 3, a KDP-backed brigade of Syrian Kurdish fighters, the so-called Rojava Peshmerga (“Rojava” denoting “western” or Syrian Kurdistan), moved from the Mosul area toward a PKK garrison in Khanasur, a village on the border, provoking a fire fight in which a number of fighters on both sides were killed and injured. Then, on March 14, the PKK retaliated with a provocation of its own, busing hundreds of Syrian civilians into the area, who started a demonstration in Khanasur. Unable to push back the throng, the Rojava Peshmerga opened fire. In the melee, a young woman operating a video camera was killed and several other protesters were injured.

Iraqi Kurdish leaders have dismissed these skirmishes as a PKK attempt to test the commitment of their forces, and say they do not seek a broader conflict. But wars are not always started by deliberate actions. The potential for escalation in Khanasur or elsewhere in Sinjar is significant, given the close proximity in which the two sides’ fighters have deployed, the mutual enmity between them, and the complete lack of trust among their leaders. There is also the problem that Turkey’s tolerance of PKK activity on its borders with Iraq and Syria appears to have reached a breaking point. How it will act next may depend on whether its leader, Recep Tayyip Erdoğan, never less than mercurial, wins an April 16 national referendum that would give him sweeping new executive powers.

A Kurdish opposition politician in Suleimaniya described to me what he saw as the worst-case, doomsday scenario in Iraqi Kurdistan:

The KDP attacks the PKK in Sinjar; Turkey sends more of its forces into Iraq to support the KDP; PKK fighters start moving down from Qandil toward Erbil, attacking KDP positions and threatening President Barzani’s palace at Sari Rash; the KDP calls on the PUK [the other Iraqi Kurdish party with peshmerga forces, the Patriotic Union of Kurdistan] to block the PKK’s path, which it controls; the PUK, which harbors sympathies toward the PKK, decides to stay neutral; PUK-KDP relations take a nosedive, and we will have civil war again.

This politician was not the only one warning of the dark consequences of renewed fighting between the Kurds; officials of the Kurdistan Regional Government in Erbil raised similar fears. They all can recall an earlier round of such conflict, in the 1990s, when the KDP and PUK faced off for four years over disputed customs fees and deep political differences. That conflict was also precipitated by the PKK, and involved a similar Iranian effort to use the PKK to gain control of a corridor across northern Iraq, in that case from Haj Omran in the east to Fish Khabour on the Tigris in the west, using the PKK as enabler. Somehow every recent development in the conflicts in Syria and Iraq seems to have a precedent to which it bears a striking resemblance. Is the region condemned to never-ending cycles of ethnic and sectarian bloodletting fed by historic grievances, unfulfilled ambitions, and mutual rancor?

Local leaders have learned that when your ambitions are stymied, you can call on external powers to come to your aid. While the Syrian conflict is the most powerful recent example of this phenomenon, Kurdish parties have a long history of it. They have not been averse even to offering to trade away resources—for example, access to Kirkuk’s oil—to achieve their larger goals. These include everything from getting weapons and guarantees of protection to obtaining pledges of support for greater autonomy and a path to independence. Ultimately, they seek international recognition of their status. The Kurds’ first port of call has tended to be the United States, but they have found that while US support can be critical to their fortunes, it is also fickle, and bound to evaporate as soon as Washington shifts its attention or decides to throw its weight behind its crucial NATO partner Turkey, with its large army and bases for US military activity in the region. The US also persists in its commitment to post-Ottoman national borders; it may express sympathy for Kurdish aspirations, but it doesn’t support an independent Iraqi Kurdistan and it knows that Kurdish independence is a function of Turkish and Iranian consent, which both have withheld. This is not likely to change anytime soon.

The Trump administration has the potential to tamp down the conflict over Sinjar and to prevent an intra-Kurdish war, just as the Clinton administration mediated a peaceful end to Kurdish fighting in the 1990s. The US has strong bonds with the KDP, forged in Iraq’s post-2003 chaos and reinforced in the current fight against ISIS. Paradoxically, at the same time, the US has also developed an effective military relationship with the YPG, the military wing of the PKK in Syria, which has used US weapons and military advice to wrest several Syrian towns from ISIS control. Backed by US support, the YPG is now poised to capture ISIS’s self-proclaimed capital in Raqqa, which could deal the jihadist group a death blow.

The problem with this US-YPG alliance, apart from the fact that the YPG is a branch of an organization that is on the US terrorism list, is that the US commitment to these Kurdish fighters is wafer thin: it could well come to an end the moment the YPG achieves victory in Raqqa. The US has yet to articulate a vision for a post-ISIS governance of Raqqa and other areas; it is possible that these could fall into local Arab or even regime control. The Trump administration’s backing for Iraqi Kurdistan is not much more certain. The White House seems disinterested in the use of diplomacy in faraway battlefields and is showing scant regard for even some of its staunchest allies.

So will the US betray the Kurds’ hopes, as it has been accused of doing before? It is not uncommon to hear even US officials decry Washington’s “short-termism,” which is informed by electoral cycles and adjustments in foreign policy priorities, and express grudging admiration for Iran’s planning and strategic patience. To Iran, the US has a fly-by-night approach to the region, and is easily deterred from apparent commitments that suddenly look costly or do not clearly connect with deeper US interests.

But recent events in Syria may drag a reluctant Trump administration back in, because if anything energizes Washington, it is the possibility of a growing Iranian threat to Israel and US interests in the region. And Russia is unlikely to accede to US demands to distance itself from Assad. It will continue to support the Syrian regime, and it needs Iranian help to do so.

The window for American mediation in Sinjar is bound to close within the next year as the battle against ISIS winds down. The Trump administration has the option to use its leverage with both PKK and KDP to reduce tensions there. This will require an arrangement that sees the departure of non-Iraqis from the area (both PKK commanders and the Rojava Peshmerga); the deployment of a security force consisting of local Yazidis in Sinjar and surrounding areas, protected by a joint perimeter force of Iraqi soldiers and Kurdish peshmerga; and local Yazidi self-government. This may appease Turkey and could bring a temporary peace to the area, but it will hardly address the matter of Iranian ambitions.

The question is how Trump will respond: through confrontation or containment? If the latter, the way forward will be through a negotiated settlement of the Syrian conflict—one that would have to include not only Russia but also Iran, the Syrian regime itself, and, on the other side, Turkey and Syrian insurgents. At the same time, the US and its allies would need to persuade Turkey and the PKK to resume peace talks. Both these goals seem distressingly far-off. But if Trump decides on confrontation, then the region is likely to lose what little stability it has left.