Now Playing: Trump declares national emergency over border wall funding

Now Playing: Scientist born in China accused of stealing trade secrets

Now Playing: White House press secretary Sarah Sanders says she was interviewed by Mueller team

Now Playing: US sanctions top Venezuelan security officials as Maduro digs in

Now Playing: Supreme Court agrees to hear 2020 census citizenship question case

Now Playing: Stacey Abrams reflects on campaign loss

Now Playing: President Trump declares national emergency and claims $8 billion to secure border

Now Playing: Trump's physical results show weight gain, but he's 'in good health overall': WH

Now Playing: Trump is expected to declare a national emergency

Now Playing: President Trump declares national emergency for border wall funding

Now Playing: SPECIAL REPORT: President Trump declares national emergency for border wall funding

Now Playing: Video shows arrest of Texas man in 3D-printed gun case

Now Playing: Judge: Trump's former campaign chairman lied to the special counsel team

Now Playing: 21 Savage released on bond by Immigration and Customs Enforcement

Now Playing: Rep. Ilhan Omar responds to attack from Trump

Now Playing: Susan Collins 'disappointed' Trump will declare national emergency

Now Playing: One-on-one with EPA Administrator Andrew Wheeler

Now Playing: Countdown to another possible govt shutdown as new border deal hits snag

Now Playing: William Barr confirmed by Senate to become attorney general

Now Playing: McConnell: Trump will sign border bill, declare national emergency