DescriptionLast week, the Trump administration reversed U.S. policy and said the Syrian dictator Bashar Assad did not have to leave power. The nerve gas attack came five days later, and now, the administration reversed its policy again. Margaret Brennan reports.Subscribe to the "CBS Evening News" Channel HERE: http://bit.ly/1S7DhikWatch Full Episodes of the "CBS Evening News" HERE: http://cbsn.ws/23XekKAWatch the latest installment of "On the Road," only on the "CBS Evening News," HERE: http://cbsn.ws/23XwqMHFollow "CBS Evening News" on Instagram: http://bit.ly/1T8icTOLike "CBS Evening News" on Facebook HERE: http://on.fb.me/1KxYobbFollow the "CBS Evening News" on Twitter HERE: http://bit.ly/1O3dTTeFollow the "CBS Evening News" on Google+ HERE: http://bit.ly/1Qs0aamGet your news on the go! Download CBS News mobile apps HERE: http://cbsn.ws/1Xb1WC8Get new episodes of shows you love across devices the next day, stream local news live, and watch full seasons of CBS fan favorites anytime, anywhere with CBS All Access. Try it free! http://bit.ly/1OQA29B---The "CBS Evening News" premiered as a half-hour broadcast on Sept. 2, 1963. Check local listings for CBS Evening News broadcast times.