– A bloody rivalry has emerged between extremist groups in Somalia as the al-Qaida-linked al-Shabab hunts upstart fighters allied with ISIS, who have begun demanding protection payments from major businesses, officials tell the Associated Press.

The rivalry supports some observers’ suspicions that al-Shabab, now rushing to defend its monopoly on the mafia-style extortion racket that funds its high-profile attacks, is drifting from its long-declared goal of establishing a strict Islamic state.

The manhunt began in October with the killing of a top leader of the ISIS-linked group by a suspected al-Shabab death squad in the capital, Mogadishu, according to several Somali intelligence officials, who spoke on condition of anonymity.

When the body of Mahad Maalin, deputy leader of the ISIS-affiliated group, was found near a beach in Mogadishu, it set off a hunt for suspected ISIS sympathizers within al-Shabab’s ranks, officials said. Maalin had been suspected of trying to extend his group’s reach into the capital.

The ISIS-affiliated group in Somalia, largely made up of al-Shabab defectors, first announced its presence in 2016 with attacks in the far north, far from Mogadishu and most al-Shabab strongholds. Though estimated at a few hundred fighters at most, their emergence in one of the world’s most unstable countries has been alarming enough that the U.S. military began targeting it with airstrikes a year ago.

The revelation by businessmen that ISIS-linked operatives had begun making extortion demands took al-Shabab’s leadership by surprise, prompting the manhunt that has led to assassinations and the detention of over 50 suspected ISIS-linked extremists, including foreign fighters, two Somali intelligence officials told AP. One suspected ISIS-linked fighter from Egypt was shot dead on Nov. 18 in Jilib.

While extortion is the fighters’ latest tactic it is nothing new in Somalia, where al-Shabab has long used death threats and other intimidation to pressure businesses to pay what is called “zakah,” or charity. The money is their main source of funding. “Indeed, al-Shabab is likely generating a significant budgetary surplus,” the U.N. panel of experts said, noting that one of its checkpoints brought in about $10 million a year.

With no strong government to protect them, businessmen often say they have no choice but to pay in exchange for protection.