Question: who has the power to launch nuclear weapons in the us
[{'answer': 'Only the President', 'provenance': [{'wikipedia_id': '255151', 'title': 'National Command Authority', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::Authorization of a nuclear or strategic attack.\n'}]}]