With millions gathering in Washington D.C. for the inauguration of President-elect Donald Trump, there's a potential threat high up in the sky many won't see.
Kerry Sanders and Matthew Vann, NBC News
Thu, 01/19/2017 - 9:50am
With millions gathering in Washington D.C. for the inauguration of President-elect Donald Trump, there's a potential threat high up in the sky many won't see.