What we know about the US air strikes in Nigeria

After the United States launched strikes targeting IS bases in northwest Nigeria on Christmas Day, questions remain concerning the strategy and details of the operation.

Here is what we know:

Who was involved?

US President Donald Trump was the first to announce the strikes, initially raising concern among Nigerians that their sovereignty may have come under attack.

Later, both countries said that they were involved and that the strikes had the approval of Nigerian President Bola Tinubu.

The Nigerian military was involved at some level, and according to Nigeria's Information Minister Mohammed Idris, the attack was carried out with the "full involvement of the Armed Forces of Nigeria".

Which group was targeted?

Washington said it targeted militants linked to the Islamic State group, and the US African command said there were multiple casualties, without providing details of precise targets among the multiple armed groups operating in Nigeria.

But Nigeria said two major Islamic State (IS) terrorist enclaves located within the Bauni forest in Tangaza Local Government Area of Sokoto state, were struck.

Analysts questioned the choice of striking northwestern Sokoto state, where armed criminal gangs -- known as "bandits" -- are a bigger concern than jihadists, who may not even have been hit by the strikes.

Nigeria's foreign minister said there are several terrorist groups and armed gangs of bandits, listing "activities of JNIM, of ISWAP as well as Lakurawa and Mahmuda".

The main theatre of the country's years-long jihadist insurgency is in fact the northeast of Nigeria.

"If you're going to strike then it shouldn't be the least" affected areas, said Victoria Ekhomu, an analyst and head of the Association of Industrial Security & Safety Operators of Nigeria.

She said a more obvious target would have been northeastern Borno state, the epicentre of Nigeria's jihadist conflict.

However, US and Nigerian officials have said that there will be more strikes to come.

How were the strikes conducted?

The US used guided missiles launched from large Reaper drones kept on "maritime platforms domiciled in the Gulf of Guinea", said Abuja, with some munitions debris falling in Jabo village of Tambuwal Local Government Area in Sokoto state as well as in nearby Kwara state, near a hotel.

No civilians were injured, according to the Nigerian government.

What is known about Islamic State group in Nigeria

Nigeria has been battling a jihadist insurgency in its northeast since 2009, waged by Boko Haram and rival offshoot Islamic State West Africa Province.

Several other groups, some of them associated with the northeastern jihadists, have established themselves in the northwest.

Some researchers have recently linked an armed group known as Lakurawa -- the main jihadist group located in Sokoto State -- to Islamic State Sahel Province (ISSP), which is mostly active in neighbouring Niger and Mali, although others are doubtful.

Research on Lakurawa is complicated, as the term has been used to describe various armed fighters in the northwest.

Fears are also growing that another powerful Sahel jihadist group, Al-Qaeda affiliated Group for the Support of Islam and Muslims (JNIM), might establish itself in Nigeria following an attack claimed by its fighters on the Nigeria-Benin border in October.

What about the timing?

Trump unexpectedly turned on Nigeria in November, accusing its government of allowing a "genocide" of Christians -- a framing that has long been used to describe the country's myriad conflicts by the US and European religious right.

The Nigerian government and independent analysts reject the accusations, pointing out that Nigeria's multiple, sometimes overlapping conflicts have killed Muslim and Christian civilians alike.

Following weeks of intelligence gathering, including US recon flights tracked by open source analysts, the timing of the strikes on Christmas Day may be significant.

"The fact that it was Christmas when we were trying to celebrate the birth of Jesus Christ" suggests Trump "has his own agenda, and ... he's focused on Christians," said Ekhomu.

Security analyst Brant Philip, writing on X, suggested the timing was "a symbolic start to official US operations in Nigeria", adding: "The operational results of the strikes are not significant, but much is expected soon."