It’s not clear which group the US targeted in Nigeria, with a few different IS-affiliated groups in the country.
Donald Trump only said they were “ISIS terrorist scum”.
That group – self-styled as Islamic State – emerged in Iraq and Syria and quickly created a “caliphate”, declaring its rule over all Muslims.
It reached its height between 2014 and 2017, when they held parts of the two countries and ruled over millions of people.
It even had a base a mere 30-minute drive from Baghdad, Iraq’s capital.
IS tried to rule like a centralised government, and imposed its interpretation of Sharia law strictly, carrying out public executions and torture.
Fighters also carried out – or influenced – attacks in dozens of cities around the world.
After a sustained military campaign by a US-led coalition, the caliphate eventually collapsed in Iraq and in Syria
Where is it now?
After it was driven from its bases in the Syrian city of Raqqa and the Iraqi city of Mosul, the group took refuge in the hinterlands of the two countries.
It still has a significant presence in Syria and Iraq, parts of Africa, and in Afghanistan and Pakistan.
Affiliates are active in southern parts of the Philippines, where pro-IS militants controlled the city of Marawi in 2017.
IS leadership is clandestine and its overall size is hard to quantify, with fighters scattered in autonomous cells.
The UN reckons it has a membership of 10,000 in IS heartlands.
Meanwhile, foreign fighters have joined Islamic State’s Khorasan branch – which you may have seen is referred to as ISIS-K.
What are its tactics?
IS has always wanted to spread its extreme form of Islam, but it is now a disparate group, often operating through affiliates and sympathisers.
Nonetheless, it can still carry out high-profile attacks, which it claims on its Telegram channels – a social media messaging app.
There are no signs militants exchange weapons or financing.
As for its leader, the US believes the group’s current honcho is Abdulqadir Mumin, who heads the Somalia branch.
Recent attacks
Police in Australia said IS appeared to inspire the gunmen behind the shooting attack at a Jewish Hanukkah event in Sydney’s Bondi Beach, where 15 people were killed.
IS continues to plot in Syria, where the government co-operates with the US-led coalition combatting the group.
This month, two US soldiers and a civilian interpreter were killed in Syria by a suspected IS-sympathiser.
And IS has also carried out attacks in Africa, claiming an attack in Congo in October, when 43 worshippers were killed during mass at a church.
