Question: when did british troops withdraw from northern ireland
[{'answer': 'After the 1998 Belfast Agreement'}, {'provenance': [{'wikipedia_id': '7345190', 'title': 'Operation Banner', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 856, 'bleu_score': 0.868909596090053, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14845544926923143229}, 'section': 'Section::::Abstract.'}]}]