By Dianne Feinstein
Originally appeared in Politico

The first step in defeating ISIL is recognizing that the prime minister of Iraq is part of the problem.

The recent takeover of much of northern and western Iraq by the Islamic State of Iraq in the Levant, or ISIL, poses a significant threat to U.S. national security that cannot be ignored.

ISIL’s rise cannot be reversed, though, until the root cause of its ascendance is addressed, and that is Sunni disenfranchisement with the government in Baghdad.

ISIL has been successful in Iraq largely because of Sunni animosity toward the government of Prime Minister Nouri al-Maliki. His government has not governed inclusively and has fueled sectarian distrust. Simply put, Maliki needs to go.

Only with meaningful political reconciliation between Iraq’s Sunni, Shia and Kurdish parties can Iraq move forward, reestablish its territorial integrity and defeat ISIL.

ISIL is a vicious and savage Islamic extremist terrorist group that intends to build a caliphate spanning a region known as the Levant, from Lebanon through Syria and into Iraq. In fact, this week the group announced victory, declaring it has restored the 7th-century Islamic caliphate on the Iraq-Syria border. It is now simply calling itself “the Islamic State.”

During the U.S.-led war in Iraq, when ISIL was known as al Qaeda in Iraq, the group was defeated, though not eradicated. Next door in Syria, ISIL took advantage of Bashar al-Assad’s brutal assault on his own people to gain new recruits and combat experience, fighting the Syrian regime’s forces and others.

It then gained a foothold in Iraq’s Anbar province, from where it launched attacks in the northern and central parts of the country and has taken control of major cities, including Mosul.

Alarmingly, ISIL is well financed and well equipped, seizing huge caches of money and arms from the territory it has captured. It has also gained power and money through kidnappings, extortion and by seizing millions of dollars from Iraq’s banks.

ISIL’s expansion into Iraq could threaten U.S. strategic interests not only because the group has a safe haven to plan and prepare external attacks against the West, but because this crisis could easily lead to horrific sectarian violence.

Shortly after the fall of Mosul, ISIL bragged about its mass murder of 1,700 Iraqi Shia. If ISIL’s claim is true, it would exceed the number of civilians killed in the chemical weapons attack against Syrians by the Assad regime last August.

ISIL’s willingness to deploy gruesome violence against fellow Muslims has even led to a rupture between the group and al Qaeda’s traditional leadership in Pakistan. If these radicals go after Shia holy sites in Karbala and Samarra, an all-out Sunni-Shia war could ensue, engulfing the entire Middle East.

Perhaps most alarmingly, ISIL’s reach already extends to Western Europe. ISIL operatives have been arrested in France, Germany and Spain attempting to recruit what I call “passport fighters” for the war in the Levant.

ISIL wants to recruit Westerners because, after fighting on the front lines, these fighters can return to their home countries and launch terrorist attacks there. Even more ominous, existing visa-waiver programs could allow many of these European fighters to travel to the United States with little scrutiny.

The United States cannot allow this grim situation to transpire. What we should do, however, is a difficult question.

For a start, we must work with regional powers, including Iran. Both the United States and Iran have an interest in halting the spread of sectarian violence in Iraq, including preventing the destruction of Shia holy sites in Karbala and Samarra. While we have many differences with Iran, we must recognize shared goals where they exist and build upon them.

Secretary of State John Kerry recently visited Iraq to encourage its political parties to form a national government that represents all Iraqis. Grand Ayatollah Sistani has also called for an inclusive government. Iranian Foreign Minister Zarif should use Tehran’s influence to do the same.

So far, unfortunately, Iran has supplied Iraq with hundreds of tons of weapons and has dispatched military advisors to help recruit, organize and advise Shia militias. Bolstering the protection of Baghdad and other Shia cities is one thing; stoking the flames of sectarian war is quite another.

Other U.S. moves include the deployment of special operations advisers to Iraq and an increase in intelligence collection. These are the right steps to take. We must enhance the capacity of the Iraqi military to respond and our intelligence agencies must be vigilant of the threat ISIL poses to the United States.

We must be clear-eyed about one thing, however: The fight in Iraq has no military solution if Iraq’s political leaders fail to achieve a unity government. For the sake of a unified, stable Iraq, Maliki must step aside. Only then will it be possible to successfully confront ISIL.

Sen. Dianne Feinstein represents California in the U.S. Senate and chairs the Intelligence Committee.