ISIS, which routinely executes its prisoners, killed 930 members of the opposition Shaitat tribe.

ISIS has executed nearly 2,000 people in Syria – half of them from an important Sunni tribe – since announcing their “caliphate” in June, a monitoring group said Sunday.

“The Syrian Observatory for Human Rights has documented the execution by the Islamic State of 1,878 people in Syria between June 28 when it announced its ‘caliphate” and December 27,” the group said in a statement.

The dead included 930 members of the Shaitat tribe which rose up against ISIS in the eastern province of Deir Ezzor in the summer, the UK-based Observatory said.

On Dec. 17, the Observatory said a mass grave containing the bodies of 230 Shaitat had been found in the province.

The monitoring group, which relies on a network of activist and medical sources on the ground in Syria, said the victims were shot dead, beheaded or stoned to death in the provinces of Aleppo, Deir Ezzor, Hama, Homs, Hasakeh and Raqqa.

Women, children included

Of those killed, 1,175 were civilians who included four children and eight women.

The militants also “executed” 502 soldiers and pro-regime militiamen, the monitoring group said.

It said ISIS also killed around 120 of its own members, mostly for trying to flee to their home countries, and 80 members of the rival Al-Nusra Front, the Al-Qaeda affiliate in Syria.

Despite giving a breakdown, the Observatory believes the number killed by ISIS to be far higher, given that many have disappeared and remain unaccounted for.

ISIS often records such killings on video and posts footage on the Internet, which experts say is meant to sow fear among civilians and rival groups, as well as to attract new recruits.

U.S.-led forces launch 13 strikes

To quash ISIS, U.S.-led forces on Sunday conducted eight air strikes against the militant group in Syria and five strikes on ISIS targets in Iraq, the U.S. military said in a statement.

In Syria, air strikes centered on the town of Kobani near the Turkish border, the Combined Joint Task Force said.

The strikes in Iraq included ISIS positions near Sinjar and near Mosul, the task force said.

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