Question: why did the us fight the battle of iwo jima
[{'answer': 'strategic value of the island', 'provenance': [{'wikipedia_id': '60027', 'title': 'Battle of Iwo Jima', 'start_paragraph_id': 2, 'start_character': 51, 'end_paragraph_id': 2, 'end_character': 80, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '60027', 'title': 'Battle of Iwo Jima', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 302, 'bleu_score': 0.927897523069734, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5916600188686318769}, 'section': 'Section::::Abstract.'}]}]