James M. Dubik is a retired Army lieutenant general and a senior fellow at the Institute for the Study of War. He commanded the Multi National Security Transition Command-Iraq from 2007 to 2008.

The war in Iraq was not over when the United States withdrew from Iraq in 2011. We just pretended that it was. Like it or not, our departure left a diplomatic and security vacuum that contributed to the crisis unfolding there. The government of Iraq floundered in that vacuum, promulgating the wrong domestic policies and allowing the Iraqi Security Forces (ISF) to backslide to pre-2007 performance levels. The net result has been that al-Qaeda in Iraq has not only reconstituted but expanded drawing in many of those disenfranchised and disillusioned by Iraq’s domestic policies. Worse, it has morphed into the Islamic State of Iraq and Syria (ISIS), whose stated ambition is to create a new Islamic state, absorbing parts of Syria and Iraq. As the past few days have amply demonstrated, ISIS is already more than capable of taking territory and governing.

In much of eastern Syria, ISIS serves as the de facto government. Is it advancing rapidly into northern, central and western Iraq. This week it seized Mosul, Iraq’s second-largest city; most of Baiji, home of one of the largest oil facilities in Iraq; and Tikrit. Now it is moving south toward Samarra and Baqubah, en route to Baghdad. It is already entrenched in Fallujah and Ramadi as well as in most of Iraq’s western desert. Its terror campaigns are destabilizing Baghdad and threatening Salahuddin, Tamin and Diyala provinces — the territory between Mosul and Baghdad that it wants to seize next.

While we have been debating whether ISIS fits our definition of a threat, the on-the-ground realities have been passing us by. If ISIS achieves its goal, Turkey, Jordan, Lebanon, Saudi Arabia and Iran will have a radical, fundamentalist Islamic state on their borders. Iraq will be split in two, Israel threatened and the security of the United States and the rest of the West put at significantly greater risk. The question isn’t whether ISIS is part of al-Qaeda. Rather, the question for the United States and its allies is: Do we keep pretending that the war is over or acknowledge that events in Iraq are rapidly moving in a direction at odds with our security interests? What’s our plan?

There is no use debating whether the present state could have been prevented if the United States left a sufficient residual force in place in 2011; neither Baghdad nor Washington could muster the domestic support for that. But the fact is that the Iraqis cannot succeed by themselves. If they could, the situation would not be as dire as it is.

So, what can we do now? Providing Iraq more “military stuff” isn’t a real answer, nor is the reintroduction of large numbers of U.S. or coalition troops. We have no easy options, but to start, the United States and its allies must commit to preventing an ISIS victory and assist the government of Iraq in halting and reversing ISIS’s progress. Although the long-term solutions for Iraqi stability are diplomatic and political, unless the Iraqi government can stop the ISIS offensive, such actions will be moot.

Halting the offensive is Iraq’s nearest-term objective. What is needed is a coordinated air and ground action consisting of both a heavy dose of precisely applied firepower and a sufficiently executed ground defensive. The Iraqis are incapable of such action alone. The firepower will have to be delivered by United States and allied aircraft augmented by Iraqi assets. The Iraqis will also need a small group of advisers to target air support correctly and to help identify or create capable, well-led units that are properly employed and backed by sufficient sustainment capacity. The advisory and support effort must be substantial enough to help the Iraqis conduct an initial defense and then plan and prepare a series of counter-offensive campaigns to regain lost areas. This will be a multi-year effort, but it cannot become a second surge.

These security actions must be taken within the context of an aggressive diplomatic and political effort. The United States and its allies must insist that Iraqi Prime Minister Nouri al-Maliki dissolve the nefarious Office of the Commander-in-Chief, which has been one of the primary causes of the erosion of the ISF. The prime minister must also cease being the de facto ministers of defense and interior. Centralizing security ministries and running security operations from his office have all but ended development of both ministries, politicized the police and the military and reduced the performance of the ISF. Finally, the government of Iraq must change policies so that fewer Iraqis feel excluded. The failure to do so has helped create the crisis of confidence in Iraq’s government.

But, again, unless the ISIS offensive campaign is stopped and reversed, none of this will matter.

These would be drastic actions, and they can succeed only if Iraq is convinced that it is facing an existential threat and must change course. The United States and its allies, too, must be convinced that an ISIS state poses a national security threat. No one likes the options before us, but we’ll like even less what happens if we do nothing or take only ineffective action.