ugust: The Islamic State beheaded a Lebanese Army soldier whom they had kidnapped. The group also beheaded a Kurdish Peshmerga fighter in response to Kurdistan's alliance with the United States, and executed around 250 Syrian soldiers captured after the fall of Tabqa Air Base in Ar-Raqqah province. The soldiers had earlier been marched to their place of execution wearing just their underwear.
29 August: UK Prime Minister David Cameron raised the UK's terror level to "severe" and committed to fight radical Islam "at home and abroad".
31 August: Iraqi military forces supported by Shia militias and American airstrikes broke the two-month siege of the northern Iraqi town of Amerli by Islamic State militants. German Federal Minister of Defence Ursula von der Leyen announced that Germany will send enough weapons to arm 4,000 Peshmerga fighters in northern Iraq fighting Islamic State insurgents. The delivery to be scheduled in stages will include 16,000 assault rifles, 40 machine guns, 240 rocket-propelled grenades, 500 MILAN anti-tank missiles with 30 launchers and 10,000 hand grenades, with a total value of around 70 million euros. In order to assess the needs of the Peshmerga and prevent an excessive accumulation of arms, the Bundeswehr seconded six liaison officers to Erbil who will report to Berlin.
1 September: The German government's Cabinet decision to arm the Kurdish Peshmerga militia was ratified in the Bundestag by a "vast majority" of votes, after an emotional debate.
2 September: The IS released a video showing the beheading of a man whom they identified as American journalist Steven Sotloff.
5 September: The German Bundeswehr dispatched the first of a planned series of cargo planes to Iraq, loaded with helmets, vests, radios, and infrared night-vision rifle scopes. After a three-hour stopover in Baghdad for inspection, the aircraft will deliver the equipment to German personnel already in Erbil for distribution to the Kurdish fighters.Qassem Soleimani, Commander of the elite Iranian Revolutionary Guard Quds Force, has been to the Iraqi city of Amirli, to work with the United States in pushing back militants of the Islamic State.
8 September: The Islamic State carried out a double suicide attack in a town north of Baghdad killing 9 people and wounding 70 others.
10 September: After ISIS had outraged American opinion by beheading two American journalists and had seized control of large portions of Syria and Iraq in the face of ineffective opposition from American allies, President Obama decided on a new objective for a rollback policy in the Middle East. He announced: "America will lead a broad coalition to roll back this terrorist threat. Our objective is clear: We will degrade, and ultimately destroy, ISIL through a comprehensive and sustained counterterrorism strategy."
12 September: A Western-backed Syrian rebels group operating around Damascus and the Islamic State signed a "non-aggression" agreement.
Conspiracy theorists in the Arab world have advanced false rumors that the US is secretly behind the existence and emboldening of ISIS, as part of an attempt to further destabilize the Middle East. After the rumors gained viral status, the US embassy in Lebanon issued an official statement denying the allegations, calling them a complete fabrication. Others are convinced that ISIS leader Abu Bakr al-Baghdadi is an Israeli Mossad agent and actor called "Simon Elliot". The rumors claim that NSA documents leaked by Edward Snowden reveal this connection. Snowden’s lawyer has called the story "a hoax".
^The Islamic State was previously known as the Islamic State of Iraq and the Levant (ISIL), alternately called the Islamic State of Iraq and Syria (ISIS) or the Islamic State of Iraq and ash-Sham (referring to Greater Syria; Arabic: الدولة الاسلامية في العراق والشام ad-Dawlah l-ʾIslāmiyyah fīl-ʿIrāq wash-Shām). The group is also known by the Arabic acronym DAʿESH (Arabic: داعش Dāʿesh). These names continue to be used.
^According to classical Islamic sources, Hilf al-Mutayyabin was an oath of allegiance taken in pre-Islam