The US launched air strikes targeting Islamic State militants in north-west Nigeria on Thursday.

The attacks marked a major escalation in an offensive that the West African nation's overstretched military has struggled with for years.

With US President Donald Trump hinting at plans for further strikes, here's a rundown on what you need to know about the conflict.

What happened on Thursday?

The US carried out "powerful and deadly" air strikes against Islamic State militants in Nigeria's north-western state of Sokoto at the request of the Nigerian government.

US President Donald Trump broke the news in a post on his social media website Truth Social.

He said the militants had been "viciously killing, primarily, innocent Christians".

Nigeria said the strikes were part of an exchange of intelligence and strategic coordination between the two countries.

In an interview with Politico on Friday, the president said he decided on the timing of the strikes to coincide with Christmas Day.

"They were going to do it earlier," he said.

"And I said, 'Nope, let's give a Christmas present.'"

What has Trump said about future strikes?

Further into his social media post that discussed the strikes carried out on Thursday, Mr Trump suggested there could be more US-led attacks to come.

"I have previously warned these Terrorists that if they did not stop the slaughtering of Christians, there would be hell to pay, and tonight, there was," he wrote.

"Under my leadership, the Country will not allow Radical Islamic Terrorism to prosper.

"May God Bless our Military, and MERRY CHRISTMAS to all, including the dead Terrorists, of which there will be many more if their slaughter of Christians continues."

Donald Trump suggested more air strikes could be ordered.  (AP: Alex Brandon)

US Secretary of Defense Pete Hegseth also posted about the strikes on social media, saying there would be "more to come …"

"The President was clear last month: the killing of innocent Christians in Nigeria (and elsewhere) must end," he wrote.

"The @DeptofWar is always ready, so ISIS found out tonight — on Christmas."

What is the security situation in Nigeria?

The Nigerian government has been struggling with a complex security situation for some time.

Several armed groups are active in the country, each with differing motives, and both Muslims and Christians are being targeted.

Gangs are often driven by the near absence of security in conflict hot spots, which makes recruitment easy.

Those hot spots have some of Nigeria's highest poverty, hunger and unemployment levels, according to data.

Nigeria's Minister of Defence Christopher Musa has said military action is only 30 per cent of what is needed to resolve the security crisis, while the remaining 70 per cent depends on good governance.

"The absence of the state in remote communities is making it easy for non-state actors to come in and present themselves to the people as the best alternative government," said Malik Samuel, a Nigerian security researcher with Good Governance Africa.

Nigeria's military struggles to respond to the breadth of security threats across the country. (Reuters: Afolabi Sotunde)

Nigeria's security forces are often overstretched and outgunned as they address the multiple crises across different regions.

The military often carries out air strikes on militant hideouts in states like Sokoto.

But analysts say military operations targeting the gangs are not usually sustained and the militants easily move on motorcycles to new locations through vast forests that connect several states in the north.

They also often use hostages — including schoolchildren — as cover, making air strikes difficult.

Who are the militant groups operating in Nigeria?

There are a handful of armed groups affiliated with Islamic State: The Islamic State West Africa Province and the lesser-known Lakurawa group, which is affiliated with the Islamic State Sahel Province.

The Islamic State West Africa Province is an offshoot of the extremist group Boko Haram and operates in the north-east of Nigeria.

Lakurawa is prominent in the north-west.

Officials did not say which group was targeted, but security analysts have suggested it was likely members of Lakurawa, which became more lethal in border states like Sokoto in the last year.

Several analysts say Lakurawa has been active in the region since around 2017, when it was invited by traditional authorities in Sokoto to protect their communities from bandit groups.

But James Barnett, an Africa researcher with the Washington-based Hudson Institute, said the militants "overstayed their welcome, clashing with some of the community leaders … and enforcing a harsh interpretation of Sharia law that alienated much of the rural population".

Mr Samuel says communities now openly see Lakurawa as more oppressive and dangerous than the bandits they claim to protect them from.

He said Lakurawa controls territories in Sokoto and Kebbi states, and has become known for killings, kidnapping, rape and armed robbery.

The Nigerian military has said in the past that Lakurawa has roots in the country's northern neighbour, Niger, and that it became more active in Nigeria's border communities following a 2023 military coup.

That coup resulted in fractured relations between Nigeria and Niger and affected their multinational military operations along the porous border.

How many Christians have been killed in Nigeria?

Mr Trump says thousands of Christians have been killed in targeted attacks by the militant groups in Nigeria.

Previously, Republican senator Ted Cruz has claimed more than 50,000 Christians had been killed by Boko Haram in Nigeria since 2009, and more than 18,000 churches destroyed.

On his podcast in September, Mr Cruz cited a 2023 report by the International Society for Civil Liberties and Rule of Law — a non-government organisation that monitors human rights abuses in Nigeria — which appears to have originated the 50,000-person statistic discussed in the US.

The report also estimated 34,000 Muslims had been killed in the same period.

But analysis by the BBC found those numbers are based on news reports of deaths, where the religion of those killed was not published, making them likely inaccurate.

Experts say it's difficult, if not impossible, to accurately determine fatalities by religious groups and instead stress that all religions in Nigeria have been affected.

A mosque in the north-western state of Borno was attacked during evening worship on Thursday amid heightened violence. (Reuters: Ahmed Kingimi)

They argue it's inaccurate to frame the situation as one targeting only Christians, who are predominant in the south, while Muslims make the majority in the north.

A statement by Minister of Information and National Orientation Mohammed Idris in September said portrayals of the security crisis as a campaign against a single religious group was "a gross misrepresentation of reality".

"Nigeria's security challenge is not a war of religion,"

he said.

"Terrorists attack all who reject their murderous ideology — Muslims, Christians, and those of no faith alike."

Gimba Kakanda, a senior special assistant to the Nigerian president on research and analytics has said descriptions of the crisis as a religious war "betray ignorance of the country's internal dynamics".

He wrote in October that both Muslim and Christian communities have alleged genocides during the decades of security conflict in Nigeria.

"In reality, Nigeria's conflicts are multi-faceted, driven by ethnic rivalries, land disputes and criminality, with religion often secondary," he wrote.

He added that most of Boko Haram's victims were Muslim, though the group has not positioned itself against any single religious group.

What is Islamic State?

Islamic State was once known as "the world's deadliest terror group".

It ruled large parts of Iraq and Syria from 2013, though its caliphate was defeated, and its leader was assassinated by US Special Forces in Syria in 2019.

Professor Amin Sabaileh, a terrorism expert at the Hume Institute in Lausanne, told the ABC earlier this month that in recent years, the group has been gaining ground again with new operative models.

You can read more about how the terror group operates in this article by Middle East correspondent Eric Tlozek and Chérine Yazbeck. 

AP/ABC