The U.S. invasion of Iraq and subsequent dismantlement of Saddam Hussein’s regime created a vacuum at the center of the Gulf and the Arab world. Now many regional forces, governmental and otherwise, have entered the fray. Ironically, the departure of U.S. troops from Iraq in 2014 has created an even more dangerous vacuum.

Back in 2003, Al-Qaeda in Iraq (AQI) was the most threatening player for Iraq, the region, and the United States. Of the several state actors empowered by the U.S. invasion, Iran was the most powerful and most antagonistic to U.S. and Western interests in the Middle East. When American forces departed from Iraq, they left behind a weak military, a political stalemate, and an even larger void into which the Islamic State in Iraq and Syria (ISIS) has stepped in. The armed movement is potentially more dangerous than anything that preceded it in the past ten years. The Obama administration’s current efforts against ISIS are of a tactical nature and will not serve to defeat or dislodge it from the areas it now occupies.

Under current conditions in Iraq, the airstrikes ordered by President Obama are, by the admission of the administration, a stop-gap measure with limited goals: to stop the advance of ISIS forces on Erbil, home of the U.S.-favored Kurdish forces and site of a U.S. consulate housing diplomats, along with civilian and military advisors, and to provide humanitarian relief to a beleaguered group of Yazidis sheltering on a mountain top from ISIS fighters surrounding them. Sustained airstrikes may indeed slow the advance of ISIS on Erbil, an advance that was itself an unlikely and tactically unsound move on the part of the Islamist group. Likewise, though more difficult, the delivering humanitarian relief to the Yazidis—one of the many minority ethnic and religious groups living in Iraq for centuries and holding, in this case, Zoroastrian beliefs considered heretic by the fundamentalist Islamists of ISIS—is also quite feasible. The realties on the ground, however, are unlikely to be altered in the near term. ISIS’s advance toward Erbil, likely a move to put the Kurdish forces on the defensive, should be easy enough to stop. Strategically, however, the likely next step for ISIS is to hold and consolidate its control of northwestern Iraq and prepare for further expansion southward and westward in Syria, and southward in Iraq at a more convenient moment for their forces.

Even though the ideology of Al-Qaeda and that of ISIS’s are almost identical, indications are that ISIS is a more potent, and therefore more dangerous, organization than AQI. As lethal as the latter was, it remained an underground movement engaged in random acts of violence and terrorism that did not lead to any gains on the ground for the organization and its supporters. ISIS, by contrast, is acting very strategically, conquering territory and amassing the means to hold, consolidate, and possibly advance further into the Levant region. ISIS has further established a rudimentary system of government and is threatening to spread its control to the rest of the Islamic world. To back this rhetoric, ISIS has assembled a large army, recruiting heavily in the region and internationally. Inside Iraq, the organization has shown signs of having learnt from the mistakes of its predecessor, AQI, which alienated the Sunni community and lost its tribal leaders to coalition forces and the central government of Iraq.

ISIS’s sweep through northwestern Iraq has thus far been facilitated by the acquiescence of the Sunni population and the active participation of tribal forces against the Maliki government. Whereas AQI depended on funding from individual patrons from Iraq and the Gulf, ISIS appears to be self-funded. The organization has robbed banks; they have hijacked petrol trucks, oil refineries and, more recently, oil wells, to fund and arm themselves. ISIS has also cleverly taken over military bases in Syria and Iraq, gaining heavy weaponry in the process, notably armored vehicles and tanks. With the Iraqi army having hastily fled from major cities in the north, valuable American equipment is now in the hands of ISIS fighters, including possibly Abrams tanks. In the areas under its control, ISIS has called back to duty oil workers, engineers, and technicians to keep oil and water facilities operational and has apparently managed to sell oil and profit from it.

Crucially, ISIS has been building credibility, not only in its successes on the battlefield, but also in terms of adherence to its belief in the Levant as its natural base of operation. The organization has therefore connected areas under its control across the Syria-Iraq border, has tried to extend its control to Lebanon, and developed a support base in Jordan. ISIS is particularly sensitive to the question, What have you done for Palestine lately? Propaganda on social media networks has broadcasted answers, saying that it is not possible to liberate Jerusalem until Shia forces have been defeated. ISIS public affairs operatives have used examples from wars the Prophet Mohammed fought against internal enemies and wars Saladin fought against the crusaders to justify its decision to delay confrontation with Israel for the time being.

Starting from its points of origin inside Iraq, ISIS gained strength and notoriety in Syria, taking full advantage of the prolonged chaos and power vacuum there. The Obama administration’s neglect to follow through on pronouncements that “Assad must go,” and failure to support the secular opposition in Syria at a time when the Islamist forces were either weak or non-existent, were instrumental in the growth of ISIS. The belated deliveries of small arms to the Free Syria Army (FSA) in 2013 and $500 million in lethal aid were too little too late. In a three-way race between the regime, Islamists, and the FSA, Syria’s so-called ‘moderate’ rebels are the weakest. The regime, bolstered by direct assistance from Iran and Hezbollah, has consolidated its hold on the third of the country adjacent to the Lebanese border, the Mediterranean, and encompassing most of the urban areas of the country. ISIS and the Islamist Nusra Front have between them taken over most of the rest of the country.

There are no good options for the U.S. administration at this point, only bad and worse ones. Any counter-offensive to dislodge ISIS would have to include large forces on the ground, something the president has ruled out. This leaves two options for Washington: Take a deep breath, hunker down, and focus on a long term project to arm and train Kurdish forces, hopefully in collaboration with what’s left of the Iraqi army. The long delayed adoption of the FSA would be a natural part of this strategy.

Washington’s failure to lead in these efforts will leave only one other option, which is to step aside and let Iran and Hezbollah take the responsibility for ousting ISIS, and therefore take credit and full control of Iraq after the fight is done.

Nabeel Khoury is Senior Fellow for Middle East and National Security at the Chicago Council on Global Affairs. He previously served as Deputy Chief of Mission in Yemen (2004-2007), Deputy Director of the Media Outreach Centre in London (2002-2004), and Consul General in Morocco (1998-2002). In 2003, during the Iraq war, he served as State Department spokesperson at U.S. Central Command in Doha and in Baghdad.