Washington D.C., — One year after ISIS invaded Mosul, the Iraqi city’s diverse religious heritage is on the verge of extinction, warned a U.S. government commission on Tuesday.

If appropriate actions are not taken, the U.S. Commission on International Religious Freedom (USCIRF) warned, the diverse heritage of Christians, Yazidi, Sunni and Shi’a living together could be lost completely from northern Iraq, Catholic News Agency reported.

“One year ago, the world watched in horror as ISIL captured the city of Mosul and targeted its population, including its ancient and diverse religious communities,” said commission chair Dr. Katrina Lantos Swett in a June 9 statement.

Without appropriate U.S. and international efforts, the religious heritage of Iraq and its people are in danger, Swett said.

“ISIL’s unspeakable crimes and takeover of northern Iraq could well mark the end of that nation’s formerly religiously diverse makeup.”

On June 9, 2014, troops from ISIS – also known as the Islamic State or ISIL – took the northern Iraq city of Mosul. The extreme Islamist group has declared a caliphate in the large swaths of territory it controls in Syria and Iraq.

With the takeover, the local Christian community – which has called Mosul home for more than 1,700 years – was given a choice: convert to Islam, pay a penalty tax, leave the city, or face death.

“While more than half a million people fled Mosul, those who remained have experienced killings, rape, torture, and kidnappings,” Swett explained.

In its 2015 annual report, released in late April, the U.S. Commission on International Religious Freedom said that while all Iraqi citizens are at risk due to the actions of ISIS, Yazidi and Christian minorities face particularly “egregious, devastating, and large-scale abuses, including forced expulsion from their historic homelands, forced conversion, rape and enslavement of women and children, torture, beheadings, and massacres.”

In the report, Iraq is designated as a “Country of Particular Concern” because of ISIS’ presence and government failure to protect religious minorities.

The commission has recommended that the United States and allies combatting ISIS take steps to protect “the most vulnerable communities,” including supporting or sponsoring a referral by the U.N. Security Council to the International Criminal Court to investigate ISIS action against ethnic and religious minorities in Iraq and Syria; taking concrete action to support Iraqi efforts to protect religious and ethnic minorities, and developing U.S. plans to help protect religious minorities.

The United States should also promote religious freedom within Iraq, the April report said, and should help to resettle refugees fleeing ISIS in Iraq and Syria.