On Tuesday, Islamist terrorists affiliated with the Somali group al-Shabaab attacked an upscale hotel in Nairobi, Kenya, killing at least 21. It wasnÂ’t the groupÂ’s first attack in Kenya. The radical group, which at one point was affiliated with al Qaeda, has used KenyaÂ’s heavy Somali refugee presence as cover for a number of attacks in Kenya and against Kenyans, most famously at the Westgate Mall in 2013. That Kenya remains a contributor of both soldiers and police to AMISOM, the African Union Mission in Somalia which seeks to defend the country against al-Shaabab, only puts it further in the...