Question: The former leader of the National Patriotic Front of Liberia Tom Woewiyu worked with this former former President of Liberia who resigned in which year? 
Sentence (from "Bo Waterside"): It was a key border crossing between Liberia and Sierra Leone until 1990, when it closed after the launch of Charles Taylor's National Patriotic Front of Liberia invasion from Sierra Leone.
Relevant evidence: No