On Monday, the Pentagon announced that the US had launched manned and unmanned airstrikes on Saturday that killed more than 150 militants with the al-Qaeda-affiliated group al-Shabaab in a training camp in Somalia.
This strike is shocking for three main reasons: the surprisingly high death toll, the stated reason of defending US and African Union troops from "imminent" al-Shabaab attack, and because of how it could play into al-Shabaab's rivalry with ISIS.
Way more fighters were killed in this strike than ever before
This one strike killed 150 people. For comparison, the high-end estimate of the total number of people killed by US drone strikes in Somalia between 2007, when the US began drone operations in that country, and December 21, 2015, is 126, according to data collected by the Bureau of Investigative Journalism.
In other words, more people were killed in this one strike than were killed in roughly eight years of drone strikes in Somalia. Although the US ramped up its frequency of drone strikes in Somalia beginning in 2015, this most recent strike is a fairly dramatic escalation of violence.
Previous strikes usually targeted individual leaders and were carried out using precision, drone-launched missiles, usually resulting in fewer than 10 killed in a single strike. Part of the difference here is hardware: The US used manned and unmanned aircraft, rather than just drones. But it also seems likely that the attack was so large because of the target.
US troops were in "imminent" danger of a "large-scale attack"
The militants were allegedly targeted because they were planning a "large-scale attack" and "posed an imminent threat to US and [African Union] forces," according to US Navy Captain Jeff Davis, a Pentagon spokesperson.
According to Davis and other Pentagon officials, the target was Raso Camp, an al-Shabaab training facility located about 120 miles north of the Somali capital, Mogadishu.
Davis, as reported by the BBC, said the camp has been under surveillance for a while, but that the decision to strike on Saturday was made because "[t]here was a sense that the operational phase was about to happen," and that the militants were getting ready to leave the camp to launch the attack.
No details about the actual plot itself or the exact target have been released so far. All we know at this point is that the target was US and African Union forces based in Somalia.
US forces have been engaging in covert missions on the ground in Somalia for a while now. For instance, in 2013, US Navy SEALs reportedly launched an amphibious raid in a small town in southern Somalia in an (ultimately unsuccessful) attempt to capture a "leading" member of al-Shabaab thought to be involved in the deadly Westgate shopping mall attack in Nairobi, Kenya, earlier that year that killed 67 people.
In July 2015, Foreign Policy's Ty McCormick reported that "a team of special operators from the Joint Special Operations Command … flies drones and carries out other counterterrorism activities" in Somalia.
The spokesperson for US Africa Command told McCormick that the US had sent "a limited number of trainers and advisors plus a small military coordination cell" to work with Somali and African Union troops to help "to stabilize Somalia." So that's why the US forces were there — and surely to fight al-Shabaab.
US military involvement in Somalia is legally covered by the 2001 Authorization for the Use of Military Force, in part because al-Shabaab formally pledged allegiance to al-Qaeda in 2012.
Could the strike strengthen ISIS?
Al-Shabaab, like other al-Qaeda affiliates, has for a few years now been fighting to protect its turf from ISIS. Anything that weakens al-Shabaab, even if it protects people in Somalia, also risks giving ISIS more of an opening to challenge al-Qaeda's hold there.
ISIS is challenging local al-Qaeda affiliates for control and influence in conflicts from Yemen to Afghanistan to Libya, trying to present itself as the new, tougher, more committed, more successful group and al-Qaeda as the weak old guard.
In Somalia, ISIS has been actively trying to recruit al-Shabaab fighters to abandon the al-Qaeda-linked group and join ISIS instead. So far, al-Shabaab has been pretty successful in keeping its fighters from defecting to ISIS, but it's difficult. This strike could potentially make it even harder.
The risk is that al-Shabaab's leadership could be weakened by the strike, and thus less able to fight off ISIS. Another possibility is that al-Shabaab fighters may, as a result of this week's strike, come to see ISIS as stronger and thus more attractive.
As Alexander Meleagrou-Hitchens writes in Foreign Affairs, "It isn’t hard to understand the appeal: al Shabab’s insurgency in Somalia is faltering against both African Union and Somali forces, whereas ISIS has made incredible gains in Syria."
ISIS has a limited presence in Somalia, and it has struggled to expand beyond Syria and Iraq. So it's too soon to predict whether this strike will open up Somalia for ISIS to come in. But it's a disturbing possibility nonetheless.