Feb 4 (Reuters) - (This February 4 story deletes incorrect description of Boko Haram as an affiliate of Al Qaeda in paragraph 14; corrects number of Islamic State affiliates in West and Central Africa in paragraph 15; relationship between Islamic State West Africa Province and Islamic State in the Greater Sahara in paragraph 17; and the name of Islamic State's Central Africa branch in paragraph 21)
Since the peak of its power seven years ago, when it ruled millions of people in the Middle East and struck fear across the world with deadly bombings and shootings, Islamic State has slipped back into the shadows.
Its self-declared caliphate in Iraq and Syria folded under a sustained military campaign by a U.S.-led coalition, and it has suffered other setbacks in the Middle East.
This week it lost its second leader in two years when Abu Ibrahim al-Hashemi al-Quraishi detonated explosives during a U.S. military raid in northwest Syria, killing himself and family members.
But Islamic State expanded in Africa's Sahel region last year and the chaotic U.S. withdrawal from Afghanistan may open up opportunities to strengthen its presence there.
In the core area of its insurgency, Iraq and Syria, it claimed hundreds of attacks last year. In January it launched an attempted jail-break in northeast Syria in which more than 100 prison guards and security forces were killed.
Here is a summary of the group's presence around the world.
Iraq, where the group originated, and neighbouring Syria remain the epicentre of Islamic State operations.
Once based in the Syrian city of Raqqa and Iraqi city of Mosul, from which it sought to rule like a centralised government, Islamic State now takes refuge in the hinterlands of the two fractured countries.
Its fighters are scattered in autonomous cells, its leadership is clandestine and its overall size hard to quantify, although the United Nations estimates it at 10,000 fighters in the heartlands.
Last month's attack on the jail in Hasaka holding hundreds of jihadist detainees was its largest operation since the collapse of the caliphate, showing Islamic State can still carry out large-scale and lethal operations.
While links between the leadership and offshoots in other countries may be tenuous, groups from Sinai to Somalia pledged allegiance to Quraishi when he succeeded Islamic State's founder Abu Bakr al-Baghdadi in late 2019.
A United Nations report last year estimated that in Egypt's Sinai province there may be between 800 to 1,200 fighters loyal to Islamic State.
In Libya, where it once held a strip of territory on the Mediterranean coast, the group is weaker, but could still exploit the country's ongoing conflict. In Yemen it has also been in decline.
Groups affiliated operationally or by name to Islamic State are only a part of the militant threat across Africa. Others include al Qaeda-linked groups like al-Shabaab, which is active East Africa, and Boko Haram in Nigeria.
Islamic State has two known branches in the West and Central Africa region, which include multiple affiliates.
Islamic State West Africa Province (ISWAP) formally split from Boko Haram in 2016, after a faction pledged allegiance to Islamic State the previous year. GlobalSecurity.org estimated the group had some 3,500 members in 2021.
ISWAP operates mostly around the Lake Chad area bordering Nigeria, Cameroon, Chad and Niger. It also includes Islamic State in the Greater Sahara (ISGS), an operationally independent sub-group in the border area between Niger, Mali and Burkina Faso.
The publication in March 2019 by Islamic State media of a picture of ISGS fighters under an ISWAP caption appeared to confirm a connection.
The Africa Center for Strategic Studies linked 524 violent events to ISGS in 2020, more than double the numbers of 2019, and they resulted in more than 2,000 fatalities across Mali, Niger and Burkina Faso.
The ongoing militant threat posed by various groups has been one of the main factors behind a series of military coups in West Africa over the last 18 months.
One of the deadliest groups in Eastern Democratic Republic of Congo, the Allied Democratic Forces, has been linked to Islamic State Central Africa Province by the U.S. State Department.
Although the extent of the ADF's links to the movement are murky, the United States attributed the deaths of 849 civilians to the group in 2020.
ADF killings surged by almost 50% in 2021, according to figures from the United Nations. More than 1,200 people were killed in such attacks.
Islamic State Khorasan (IS-K) - the movement's chapter in Afghanistan and surrounding areas - has emerged as the principal militant threat in the region since the Taliban took over the country in August last year.
Experts say that its main areas of operation are Central and South Asian states, and that it has been led by an "ambitious" though lesser known leader named Shahab al-Muhajir since 2020.
IS-K was first formed in 2015 with the blessing of Baghdadi, according to Western think-tanks, and was a formidable adversary to the U.S.-backed government and Taliban insurgents, even as the two fought each other.
Without international and U.S.-trained forces to contend with, IS-K activities have grown, stoking fears that Afghanistan could again become a haven for militant groups just as it was when al Qaeda attacked the United States in 2001.
"It's just about the biggest concern at the moment for everyone, in the region and in the West," a senior Western diplomat told Reuters late last year.
Moscow has voiced concern about IS-K increasing its footprint in Central Asian states.
The group has carried out a number of audacious attacks recently, most notably a complex raid on Afghanistan's biggest military hospital in November last year that killed at least 25 people and wounded more than 50.
That followed a string of bombings by the group, including a suicide attack outside the gates of Kabul airport during a chaotic U.S. evacuation operation that killed close to 200 people, including U.S. military personnel.
Figures on IS-K's strength vary. A committee of the U.N. Security Council put the number of IS-K fighters at between 1,500 and 2,200, but that was just before the fall of Kabul.
There have been reports of disaffected Taliban fighters and some Pakistani Taliban members joining IS-K in recent months. A spiralling economic crisis has pushed millions into poverty and left former Afghan Taliban fighters with no employment.
There is little to suggest direct material coordination between IS-K and Islamic State in the Middle East, but some claims of attacks carried out in Afghanistan and neighbouring areas are posted on the group's central information channels.
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