A US military raid in Somalia ordered by President Joe Biden killed a key regional leader of the Islamic State group, Bilal al-Sudani, US officials said Thursday.

Sudani was killed during a gunfight after US troops descended on a mountainous cave complex in northern Somalia hoping to capture him, according to US officials.

Around 10 of Sudani's IS associates at the scene were killed, but there were no American casualties, the officials said.

"On January 25, on orders from the president, the US military conducted an assault operation in northern Somalia that resulted in the death of a number of ISIS members, including Bilal al-Sudani," Defense Secretary Lloyd Austin said in a statement.

"Al-Sudani was responsible for fostering the growing presence of ISIS in Africa and for funding the group's operations worldwide, including in Afghanistan," Austin said.

From his mountain base in northern Somalia, he provided and coordinated funding for IS branches, not only in Africa but also Islamic-State Khorasan, the arm operating in Afghanistan, a US official said on condition of anonymity.

Ten years ago, before he joined the Islamic State, Sudani was involved in recruiting and training fighters for the extremist al-Shabaab movement in Somalia.

"Sudani had a key operational and financial role with specialized skills which made him an important target for US counterterrorism action," the official said.

- Months of planning -

The operation had been prepared over a period of months, with US forces rehearsing at a site built to replicate the terrain where Sudani was hiding.

Biden authorized the strike earlier this week after consulting with top defense, intelligence and security officials, the official said.

"An intended capture operation was ultimately determined to be the best option to maximize the intelligence value of the operation and increase its precision in challenging terrain," another administration official said.

However, "the hostile forces' response to the operation resulted in his death," the official said.

The only injury to an American in the raid was that one serviceperson was bitten by a US military service dog, the official added.

"President Biden has made it very clear that we are committed to finding and eliminating terrorist threats to the United States and to the American people, wherever they are hiding, no matter how remote," the official said.

US forces have long operated in Somalia in coordination with and on behalf of the government, mostly conducting regular aerial strikes to support official forces fighting Shabaab rebels.

Some of those are believed to be conducted out of a US base in Djibouti north of Somalia.

US aerial strikes in Somalia surged to dozens a year during 2017-2020, but also included two to four ground operations in each year.

Since Biden became president in 2021, the aerial strikes have fallen off, to just 16 in 2022, and no ground strikes have been recorded, according to data compiled by New America, a national security think tank.

The Somali operations added to three other targeted strikes Biden has ordered against Islamic extremist leaders.

In February 2022, US forces assaulted a home in northern Syria where Islamic State leader Ibrahim al-Hashimi al-Qurashi was staying.

Before the US forces could get to him, Qurashi detonated a bomb, killing himself and members of his family.

In July 2022, a US air strike in Syria killed another top islamic State leader, Maher al Agal.

And at the end of July, a US precision missile strike killed Ayman al-Zawahiri, the leader of al-Qaeda, in his apartment in Kabul.