Acting Homeland Security Secretary Chad Wolf said Nigeria (and five other countries) failed to meet U.S. security and information-sharing standards. That was the reason for Nigeria to be put on the no-entry list. (See workingimmigrants here.)
Yet a Congress Research Service report dated January 23, 2020, seven days before the ban was announced (January 31), shows that Nigeria was not on the list of countries in trouble with visa issuance.
The report says that “Countries that systematically refuse or delay the repatriation of their citizens….are considered by DHS to be “recalcitrant,” also called “uncooperative.” Countries that demonstrate some but not full cooperation are considered “at risk of non-compliance” (ARON). ICE currently classifies 10 countries as recalcitrant/uncooperative and 23 as ARON.
See this map with these countries marked here.
The report details the historical use of sanctions, including a checklist of steps the U.S. takes prior to imposing sanctions.