Over the past few months, the Islamic State, an al-Qaeda offshoot formerly known as ISIS, has mounted a brutal campaign in Syria and Iraq that has allowed it to expand its ranks and win large swaths of new territory. With the stated goal of establishing a Sunni caliphate -- or an Islamic state governed by a religious figurehead -- the insurgent group's fighting has taken a heavy toll on Iraq's Shiite Muslim majority, as well as a number of minority groups, including Kurds and Christians.

While reports of the Islamic State carrying out mass executions, placing heads on fence posts and imposing harsh religious restrictions have sparked concern across the world, they haven't elicited military involvement until now. Over the weekend, U.S. warplanes began bombing Islamist fighters following an announcement by President Barack Obama that he had authorized airstrikes to prevent "genocide."

In light of the recent news, here's an update on the militant group by the numbers: 13,000 The number of square miles thought to be under Islamic State control, a stretch between Syria and Iraq that is The, a stretch between Syria and Iraq that is roughly the size of Belgium Other estimates suggest the Islamic State controls an area closer to 35,000 square miles, or roughly the size of Jordan.

1,922 The number of people killed in Iraq in June, according to government figures, making it the deadliest month since May 2007. The, according to government figures, making it the deadliest month since May 2007. Official figures report 1,393 civilians, 380 soldiers and 149 policemen among the dead. Another 2,610 people were wounded, the majority of them civilians.

Islamic militants parade in Baiji, Iraq, on July 29, 2014.

30,000 - 50,000 The number of militants now fighting with the Islamic State, The according to a recent estimate by Dr. Hisham al-Hashimi, an expert on the group. Many former Iraqi Army soldiers have been forced to join and others have been recruited from around the region and beyond

5 The number of nations with which the Islamic State has engaged in direct fighting. In an effort to expand its holdings, insurgents have attacked soldiers from Iraq, The. In an effort to expand its holdings, insurgents have attacked soldiers from Iraq, Iran Lebanon , Syria and Turkey this summer alone. The group is currently pursuing a large offensive against the Syrian Arab Army in the northeast of the country, snatching up large quantities of munitions from military bases.

$2,000,000,000 The approximate value of the Islamic State's cash and assets, The according to estimates from terrorism experts. In the midst of its most substantial campaign in June, Islamic State fighters captured the city of Mosul, looting hundreds of million of dollars from banks and acquiring hundreds more in military assets from the Iraqi Army.

$3,000,000 The The estimated daily revenue of the Islamic State, from its oil and gas resources alone. Fighters with the group have taken control of oil and gas fields across northern Iraq and Syria, and it “now controls a volume of resources and territory unmatched in the history of extremist organizations,” according to Janine Davidson of the Council of Foreign Relations

3 The number of The number of high-profile jailbreaks carried out by Islamic State forces in the past several months, which led to the freeing of at least 1,500 insurgents, likely including leaders, bomb makers and other militants, according to reports. In an apparent response to these incidents and widespread brutality by Islamic State fighters, Human Rights Watch accused Shiite militia members and other Iraqi Army soldiers last month of having illegally executed at least 255 Sunni prisoners in at least five different massacres.

0 The number of openly practicing Christians thought to be left in the city of Mosul, where the Islamic State has made Christianity , where the Islamic State has made Christianity punishable by death . While it's impossible to know if Islamic State militants have actually chased every Christian out of the city, recent reports suggest that all remaining Christians had fled Mosul.

Up to 40,000 The The number of civilians initially estimated to have been trapped on Mount Sinjar last week after the Islamic State captured the town of Sinjar, near the Kurdish region in northern Iraq, and drove people out of the surrounding areas. While at least 20,000 were reportedly rescued over the weekend by Kurdish rebels from neighboring Syria, the remaining Yazidis are still trapped.

A family with sick children takes shelter under a sheet as thousands of Iraqis who have fled recent fighting in the cities of Mosul and Tal Afar try to enter a temporary displacement camp.

At least 500

The number of Yazidis killed so far by Islamic State fighters in northern Iraq. An Iraqi government minister told Reuters on Sunday that militants had buried some of the Yazidis alive, while they killed others in a mass execution.

At least 300

The number of Yazidi women taken as slaves by the Islamic State, according to human rights minister Mohammed Shia al-Sudani. Sudani said there are still concerns that many of the victims will be moved outside of the country, which would make it harder to rescue them. Recent reports also suggest that at least two women were publicly stoned to death by the Islamic State, one of whom faced the punishment for adultery.

500,000 According to a number of civilians who could die if the Mosul Dam, the largest dam in Iraq, stops working. Late last week, the Islamic State According to a 2011 report in Water Power magazine , this is the. Late last week, the Islamic State reportedly seized the dam , which lies on the Tigris River and provides power and water to Mosul and other parts of the region. It requires extensive engineering work to remain operational. It remains unclear what the Islamic State intends to do with it, but simply neglecting the required upkeep would potentially lead to large-scale structural failure.

65 The amount of water (in feet) that would roar toward the city of Mosul if the Islamic State decided to destroy the Mosul Dam, or if it were to suffer a catastrophic collapse for any other reason, if the Islamic State decided to destroy the Mosul Dam, or if it were to suffer a catastrophic collapse for any other reason, according to a 2007 letter from U.S. generals stressing the need to secure the dam.

1,500,000 The estimated population of Erbil, the capital of Iraqi Kurdistan. This number , the capital of Iraqi Kurdistan. This number includes an unknown number of foreign workers , some of whom are American military personnel who were dispatched earlier this summer to aid Kurdish Peshmerga fighters in their resistance efforts against the Islamic State. On Saturday, American warplanes began launching airstrikes to help Kurdish forces fighting to defend Erbil.

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