In the summer of 2014, the church bells of Mosul, the second largest city of Iraq, fell silent for the first time in nearly two millennia. Long a heartland of Christianity in the region, Mosul had been conquered by ISIS in a brutal assault. The Christians of the city were given a choice: leave, convert, or die by the sword. Most fled with nothing but the clothes on their backs.

The assault marked a major moment in ISIS’ horrific campaign of regional conquest. After capturing Mosul with the Iraqi army all but disintegrating, the so-called “caliphate” continued to metastasize across large swaths of Syria and Iraq. Marching under its black banner of death, ISIS subsequently spread into North Africa and established a wider network, beginning a global campaign of terror that has contributed to one of the greatest migrant crises in modern times. ISIS and its sympathizers have hit America and claimed lives here at home.

Fortunately, this dark tide has begun to turn. Last week, Iraqi forces, aided significantly by our weapons, air cover, and 5,000 Americans in support, initiated the largest combat operation in Iraq since 2003. Nearly 100,000 troops launched a multipronged offensive against ISIS positions around the city. Swift gains are being secured right now by the Iraqi army, Kurdish Peshmerga troops, and integrated security forces also containing the region’s beleaguered minority communities. But ISIS resistance, especially to the north and east of Mosul, seems to be fiercer and more chaotic. This region is known as the Nineveh Plain—once a thriving, pluralistic area of Iraq with a rich tapestry of religious and ethnic diversity. Battles rage around a number of towns near Mosul, including some of the oldest Christian towns in the Middle East.

The stakes of the present conflict could not be higher, especially for the minority communities to which ISIS has posed an existential threat. In March, the House of Representatives unanimously passed a bipartisan resolution I introduced that named ISIS atrocities against Christians, Yezidis, and others as “genocide,” and the legal term was recognized by the full weight and moral authority of the United States Government. This legislative maneuver was critical to further policy considerations to ensure that the horror of ISIS ends, to provide justice for the minorities, and to restore pluralism to a fragile Middle East. As a next step, in September I introduced another resolution in Congress that follows on the Government of Iraq’s own initiative to create a province in the Nineveh Plain region, with the goal of restoring the ancestral homeland of so many suffering peoples. A sustainable security settlement must be reached, including a genuine ability of indigenous peoples, supported by Iraqi and international efforts, to assure their ongoing safety.

Shortly after ISIS first invaded Iraq, in one of the rawest moments of my service in public office, a group of young men—Yezidis from Lincoln who had earned United States citizenship by serving alongside our soldiers—begged me to act. One quivered with anxiety, radiated anger, and was on the verge of tears. “There is no more time!”…“ISIS is coming”…“My mother, my sister, are trapped!” The United States did act, beginning the air campaign against ISIS and saving tens of thousands of Yezidis who were then trapped atop Mount Sinjar in Iraq.

Defeating ISIS is not just an attempt to preserve the hard fought gains of so much American sacrifice. This is more than defeating 8th century barbarians wielding 21st century weaponry—it is about humanitarian justice, stability for the Middle East, and the future of civilization itself.