Question: when did the steel and aluminum tariffs start
[{'answer': 'June 1 , 2018', 'provenance': [{'wikipedia_id': '56728490', 'title': 'Trump tariffs', 'start_paragraph_id': 30, 'start_character': 130, 'end_paragraph_id': 30, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Enacted tariffs.:Steel and aluminum.:Legal basis and challenges.\n'}]}]