Sinjar massacre

The Sinjar massacre was conducted by Islamic State (shortened IS, ISIL or ISIS) as part of the August 2014 offensive. Sinjar (شنگال Şingal) was one of many towns captured during the Islamic State's offensive in early August 2014. Zumar was also taken over by ISIS, as well as the Mosul Dam. Kurds appealed to the Government of Iraq and the United States for air support to assist their cause. Kurdish army officials Peshmerga also said to a newspaper in an interview that air strikes are needed badly to stop a possible ISIS invasion into Iraqi Kurdistan.

On 7 August, the U.S. President, Barack Obama, stated that the U.S. would use air power to assist trapped civilians threatened with acts of genocide and attack ISIS forces. Obama stated that his decision was made because U.S. "leadership is necessary to underwrite the global security and prosperity", "to protect our [American] people," to "support our allies," to "lead coalitions of countries to uphold international norms," "to prevent a potential act of genocide," and to "strive to stay true to the fundamental values—the desire to live with basic freedom and dignity."

Background
Sinjar was a predominantly-Yazidi before the ISIS takeover, and the invasion forced most to leave their homes. ISIS declared a Caliphate in June 2014 in areas of Syria and Iraq and have since gained more areas in Iraq.

ISIS take over
On the morning of 3 August, ISIS forces advanced into and captured Sinjar.

According to the United Nations, thousands of refugees were expelled from the city and lacked basic amenities. In parallel, the humanitarian disaster drew a harsh response by the Kurdish military Peshmerga and ISIS faced the first great resistance after its offensive in Iraq in June 2014. According to some reports as many as 500 Yazidis were massacred in the ISIS attack and its aftermath, and dozens more died of hunger, while fleeing the ISIS advance.

Tahseen Said, Emir of the Yazidis, issued a plea on 4 August 2014 to world leaders, concerning the plight of the people being attacked by the Islamic State.

The Yazidis were besieged by IS on Mount Sinjar, facing starvation and dehydration.

U.S. airstrikes and humanitarian aid
On 8 August, US F/A-18 fighters bombed ISIS artillery units. Four U.S. fighters later bombed an Islamic State military convoy. Another round of U.S. airstrikes in the afternoon struck 8 Islamic State targets near Erbil. Armed drones as well as fixed wing aircraft were used in the U.S. attacks.

U.S. and U.K. planes dropped food and water for Yazidis stranded on the Sinjar Mountains and surrounded by IS forces firing on them, while France pledged aid to refugees.

On 12 August, an Iraqi military helicopter, piloted by Maj. Gen. Majid Ahmed Saadi, crashed in the mountains while delivering aid and rescuing stranded Yazidi refugees. The helicopter was also carrying Yazidi lawmakers and foreign journalists. The general was the only fatality in the crash, while almost all of the passengers were injured.

On 14 August, U.S air-strikes and Kurdish fighters of the People's Protection Units from Syria, together with their PKK allies from Turkey,  broke the ISIS siege of Mount Sinjar, allowing thousands of refugees to escape.