Question: when did the us go to war with korea
[{'answer': 'the Battle of Osan', 'provenance': [{'wikipedia_id': '39332124', 'title': 'United States in the Korean War', 'start_paragraph_id': 5, 'start_character': 61, 'end_paragraph_id': 5, 'end_character': 79, 'bleu_score': 1.0, 'section': 'Section::::Battle of Osan.\n'}]}, {'provenance': [{'wikipedia_id': '39332124', 'title': 'United States in the Korean War', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 1649, 'bleu_score': 0.964355150726632, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12597630242961830120}, 'section': 'Section::::Battle of Osan.\n'}]}]