An Iraqi insurgency began shortly after the 2003 American invasion deposed longtime leader Saddam Hussein. It is considered to have lasted until the end of the Iraq War and U.S. withdrawal in 2011. It was followed by a renewed insurgency.
The Islamic Revolutionary Guard Corps, also known as the Iranian Revolutionary Guards, is a multi-service primary branch of the Iranian Armed Forces. It was officially established by Ruhollah Khomeini as a military branch in May 1979 in the aftermath of the Iranian Revolution. Whereas the Iranian Army protects the country's sovereignty in a traditional capacity, the IRGC's constitutional mandate is to ensure the integrity of the Islamic Republic. Most interpretations of this mandate assert that it entrusts the IRGC with preventing foreign interference in Iran, thwarting coups by the traditional military, and crushing "deviant movements" that harm the ideological legacy of the Islamic Revolution. Currently, the IRGC is designated as a terrorist organization by Bahrain, Canada, Saudi Arabia, Sweden and the United States.
The Badr Organization, previously known as the Badr Brigades or Badr Corps, is an Iraqi Shia Islamist and Khomeinist political party and paramilitary organization headed by Hadi al-Amiri. The Badr Brigade, formed in 1982 and led by Iranian officers, served as the military arm of the Supreme Council for Islamic Revolution in Iraq (SCIRI), a Shia Islamic party based in Iran. The Badr Brigade was created by Iranian intelligence and Shia cleric Mohammad Baqir al-Hakim with the aim of fighting the Ba'athist regime of Saddam Hussein during the Iran–Iraq War. Since the 2003 US-led invasion of Iraq, most of the Badr Brigade fighters have entered the new Iraqi army and police force. Since 2003, the Badr Brigade and SCIRI were considered to be one party, but have recently unofficially separated with the Badr Organization now being an official Iraqi political party. Badr Brigade forces, and their Iranian commanders, have come to prominence in 2014 fighting the Islamic State of Iraq and the Levant (ISIL) in Iraq. It is a part of the Popular Mobilization Forces.
The Quds Force is one of five branches of Iran's Islamic Revolutionary Guard Corps (IRGC) specializing in unconventional warfare and military intelligence operations. U.S. Army's Iraq War General Stanley McChrystal describes the Quds Force as an organization analogous to a combination of the CIA and the Joint Special Operations Command (JSOC) in the United States. Responsible for extraterritorial operations, the Quds Force supports non-state actors in many countries, including Hezbollah, Hamas, Palestinian Islamic Jihad, the Houthi movement, and Shia militias in Iraq, Syria, and Afghanistan. According to Michael Wigginton et al., the Al-Quds Force is "a classic example of state-sponsored terrorism."
The Shia Crescent is the notionally crescent-shaped region of the Middle East where the majority population is Shia or where there is a strong Shia minority in the population.
The term militia in contemporary Iraq refers to armed groups that fight on behalf of or as part of the Iraqi government, the Mahdi Army and Badr Organization being two of the biggest. Many predate the overthrow of Saddam Hussein, but some have emerged since, such as the Facilities Protection Service. The 2003 invasion of Iraq by United States-led forces undermined the internal order in the country and brought about, among other things, the establishment of several pro-Iranian militias affiliated with the Islamic Revolutionary Guard Corps's Quds Force. The militias were set up with the purpose of driving the U.S. and Coalition forces out of Iraq and establishing Iranian involvement in the country. Prominent among the militias are Asa'ib Ahl al-Haq, Kata'ib Hezbollah and Harakat al-Nujaba.
After the death of Muhammad in 632, the Muslim world split into two camps, the Sunnis, who believed that the caliphs of the Islamic community should be chosen by consensus, and a second group, the Shia who believed that Mohammed's successors should be members of his own family, beginning with Ali ibn Abi Talib, his cousin and son-in-law.
Sheik Ahmed Bezaa Abu Risha is a Sunni leader in the Al-Anbar province, and led the movement of Sunni tribesmen known as the Anbar Salvation Council.
Special Groups (SGs) is a designation given by the United States military to the cell-based Shi'a paramilitary organizations operating within Iraq. According to the United States these groups are funded, trained, and armed by the Iranian Quds Force, part of the Islamic Revolutionary Guard Corps (IRGC). According to the United States Department of Defense, 603 American troops in total were confirmed to have been killed by IRGC-backed Shia militias during the Iraq War.
Kata'ib Hezbollah, also known as the Hezbollah Brigades, is a radical Iraqi Shiite paramilitary group which is a part of the Iraqi Popular Mobilization Forces (PMF), staffing the 45th, 46th, and 47th Brigades. During the Iraq War (2003–11), the group fought against Coalition forces. It has been active in the War in Iraq (2013–2017) and the Syrian Civil War. The group was commanded by Abu Mahdi al-Muhandis until he was killed in a US drone attack in 2020. Thereafter, Abdul Aziz al-Muhammadawi became the new leader of the PMF. The group seeks to establish an Iran-aligned government in Iraq, expel American forces from the country, and advance the regional and international interests of Iran in Iraq and the region. The group is responsible for killing hundreds of U.S. soldiers and takes a central part in carrying out attacks against U.S. targets in Iraq and acts as part of the Axis of Resistance. Kata'ib Hezbollah has received extensive training, funding, logistic support, weapons, and intelligence from the IRGC's overseas military-intelligence service Quds Force.
The Axis of Resistance is an informal coalition of Iranian-supported militias and political organizations across the Middle East. Formed by Iran, it unites actors committed to countering the influence of the United States and Israel in the region.
The Free Iraqi Army was an Iraqi rebel group formed in the western Sunni-majority provinces of Iraq from Iraqi supporters of the Free Syrian Army rebels fighting in the Syrian Civil War. The group aimed to overthrow the Shia-dominated government of Iraq, believing that they would gain support in this from Syria should the rebels be successful in overthrowing Bashar al-Assad. An Iraqi counterterror spokesman denied this, saying that the name is merely being used by al-Qaeda in Iraq to "attract the support of the Iraqi Sunnis by making use of the strife going on in Syria."
From the 2000s until the fall of the Assad regime, the Islamic Republic of Iran and the Syrian Arab Republic were close strategic allies, and Iran provided significant support for the Syrian Ba'athist government in the Syrian civil war, including logistical, technical and financial support, as well as training and combat troops. Iran saw the survival of the Assad regime as being crucial to its regional interests. When the uprising developed into the Syrian civil war, there were increasing reports of Iranian military support, and of Iranian training of the National Defence Forces both in Syria and Iran. From late 2011 and early 2012, Iran's IRGC sent tens of thousands of Iranian troops and Shi'ite foreign paramilitary volunteers in coordination with the Syrian government to prevent the collapse of the regime; thereby polarizing the conflict along sectarian lines.
Beginning in December 2012, Sunnis in Iraq protested against the Maliki government. On 28 December 2013, a Sunni MP named Ahmed al-Alwani was arrested in a raid on his home in Ramadi. Alwani was a prominent supporter of the anti-government protests. This incident led to violence in Al Anbar Governorate between the Iraqi Army and a loose alliance of tribal militias and other groups fighting alongside the Islamic State of Iraq and the Levant (ISIL).
Anti-Sunnism is hatred of, prejudice against, discrimination against, persecution of, and violence against Sunni Muslims. It has also been described as "Anti-Sunni sentiment" "Sunniphobia", the "fear or hatred of Sunnism and Sunnites".
The Iranian intervention in Iraq has its roots in the post-2003 invasion of Iraq by the United States and its allies, when the infrastructure of the Iraqi armed forces, as well as intelligence, were disbanded in a process called "de-Ba'athification" which allowed militias with close ties to Tehran to join the newly reconstituted army.
Hezbollah involvement in the Syrian civil war has been substantial since the beginning of armed insurgency phase of the Syrian civil war in 2011, and evolved into active support for Syrian government forces and troop deployment from 2012 onwards. By 2014, Hezbollah was deployed across Syria. Hezbollah has also been very active in preventing Al-Nusra Front and Islamic State penetration into Lebanon, being one of the most active forces in the Syrian civil war spillover in Lebanon.
Iran and Saudi Arabia are engaged in a proxy conflict over influence in the Middle East and other regions of the Muslim world. The two countries have provided varying degrees of support to opposing sides in nearby conflicts, including the civil wars in Syria and Yemen; and disputes in Bahrain, Lebanon, Qatar, and Iraq. The struggle also extends to disputes or broader competition in other countries globally including in West, North and East Africa, South, Central, Southeast Asia, the Balkans, and the Caucasus.
The Followers of Zainab Brigade, also known as the Zainebiyoun Brigade or Zainebiyoun Division, is a Pakistani Shia Khomeinist militant group actively engaged in the Syrian Civil War. It draws recruits mainly from Shia Pakistanis living in Iran, with some also Shia Muslim communities living in various regions of Pakistan.
Akram Abbas al-Ka'abi is an Iraqi militant leader who is the founder and Secretary-General of Harakat Hezbollah al-Nujaba (HHN) in Iraq. Kaabi is a U.S.-designated terrorist who is regarded as one of the main operatives of IRGC's Quds Force in Iraq. He has been an ardent supporter and promoter of Iranian influence in Iraq while being the most outspoken critic of American military presence as he seeks to compel U.S. forces to withdraw completely from Iraq.
Iraq 
Iran (Claimed by Battat, denied by the IRGC)[ citation needed ]
Islamic State of Iraq and the Levant 
People's Mujahedin of Iran 
Free Iraqi Army 
