In FP's emailed Situation Report:
Obama announced the deployment of 300 commandos to Cameroon to work with the security forces from Cameroon, Chad, Benin, Niger and Nigeria in a bid to bolster the local effort against the Nigeria-based Boko Haram militant group.
The NYT has a little more:
Mr. Obama announced in October that he had ordered 300 troops, most of them special operators, to Cameroon ...The American troops, Mr. Obama said, would provide intelligence, surveillance and reconnaissance for the region, largely by operating unarmed surveillance drones. The troops would not engage in combat, he said.
Link:http://www.nytimes.com/2015/12/28/wo...y-answer.html?

An interesting deployment, especially as Nigeria has officially - under the current and previous presidencies - did not have good working relations. Plus to my recollection Cameroon has not had a previous US deployment, for example an elite unit was Israeli-trained.