A new Islamic State affiliate is gaining strength in sub-Saharan Africa as part of efforts by the Syrian-based Islamist terror group to take over large parts of the continent.

A relatively new group known as the Islamic State in the Greater Sahara has stepped up terrorist attacks in the swath of north Africa known as the Sahel. The Sahel is a semi-arid region that stretches from the western states of Mali and Nigeria, through Niger, Chad, and Sudan and into part of Ethiopia.

ISIS-GS, as the group is identified in U.S. intelligence reports, was formed in 2015 from al Murabitun, an Islamist terror group once linked to al Qaeda in Islamic Maghreb (AQIM). Militants from Murabitun and a second AQIM splinter group called al Mulathamun Battalion founded ISIS-GS.

According to a State Department security report, al Murabitun was "one of the more active militant groups in the Sahel" and carried out the November 2015 attack on the Radisson Blu hotel in Mali that killed 20 people.

The March 8 report by the Overseas Security Advisory Council (OSAC), a State Department-private sector group, said the new ISIS-GS had been relatively quiet for about a year before reemerging with three significant terror attacks in late 2016.

The Islamic State officially recognized ISIS-GS in October in what security analysts regard as an indication the broader terror movement is stepping up operations in northern Africa.

"Since the Islamic State proclaimed its so-called caliphate in June 2014, it has expanded in both symbolic and real terms in North and West Africa," said a report by the Combating Terrorism Center at West Point.

The OSAC report said the official ISIS recognition of the new group likely reflects "the group’s desire to strengthen its African presence after setbacks in Libya, creating a possibility that this new group could receive increased material support from ISIS in the future."

The Islamic State suffered setbacks in Libya, where it had controlled key parts of the largely ungoverned state. ISIS in Libya had imposed its ultra-violent version of Sharia law, with sex slaves and beheadings, in the city of Sirte. It was driven out of the port city in December by Libyan government forces.

Marine Corps Gen. Thomas Waldhauser, commander of Africa Command, told a Senate hearing last week that ISIS is regrouping after its expulsion from Sirte and that many of its militants were moving to southern Libya.

In prepared testimony to the Senate Armed Services Committee, Waldhauser said countering the ISIS threat in both the Sahel and Libya is among one of five "lines of effort" for his command.

"The instability in Libya and North Africa may be the most significant, near-term threat to U.S. and allies' interests on the continent," he said.

"The multiple militias and fractured relationship between factions in east and west Libya exacerbate the security situation, spilling into Tunisia and Egypt and the broader Maghreb, allowing the movement of foreign fighters, enabling the flow of migrants out of Libya to Europe and elsewhere."

The terrorist groups are working to incorporate large areas of Africa under Islamist ideology and are networking and targeting young people for recruitment, he said.

Waldhauser also stated that Africa Command "must be ready to conduct military operations to protect U.S. interests, counter violent extremist organizations, and enable our partners’ efforts to provide security."

Jason Warner, an assistant professor at the Combating Terrorism Center, stated in January that ISIS headquarters delayed recognizing the Sahel affiliate until after the attacks in late 2016. The attacks "signaled to the Islamic State that ISIS-GS was more than just a nominal fighting force," he said.

Warner said ISIS-GS appears better organized than two other new ISIS affiliates in Africa: the Islamic State in Somalia, in northern Somalia, and the southern Islamic State of Somalia, Kenya, Tanzania, and Uganda.

"While recent news on the Islamic State centers on the siege of Mosul in Iraq, the group's ideological hold in sub-Saharan Africa has been quietly growing, and not simply in relation to its well-known merger with Boko Haram," Warner wrote in the West Point journal CTC Sentinel. "Indeed, over the past year-plus, three new Islamic State affiliates have gained prominence in sub-Saharan Africa."

ISIS-GS "is the only one of these groups to have carried out multiple attacks," Warner said.

The Sahel affiliate of ISIS is led by al Murabitun commander Adnan al Sahrawi, who pledged his group's loyalty to ISIS in May 2015.

ISIS-GS conducted its first attack in Burkina Faso in September on a border post. That was followed by attacks in October in Burkina Faso and an assault on a prison in Niger in an apparent bid to free jihadists that could bolster its forces.

The Islamic State conducted similar prison attacks in Iraq prior to taking over large portions of Iraq and Syria in 2014.

ISIS-GS is also suspected of carrying out the December 2016 attack on a military convoy in Burkina Faso that killed 12 soldiers.

"The emergence of an ISIS affiliate in the Sahel will likely increase the security threat to the private sector, as western interests are routinely targeted by militant groups in the Sahel," the report said.

The Islamic terror group Boko Haram, active in Nigeria, aligned with ISIS in March 2015, another sign of the terror group's growing influence on the continent.