U.S. President Donald Trump addresses U.S. Army soldiers at a signing ceremony for the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

A soldier from the U.S. Army's 10th Mountain Division salutes U.S. President Donald Trump during the president's visit to Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump gives a thumbs up as he poses with soldiers and U.S. Army Major General Walter “Walt” Piatt, the Commanding General of the Army's 10th Mountain Division and Fort Drum, after observing a demonstration with troops, artillery and helicopters at Fort Drum, New York, U.S., August 13, 2018. REUTERS/Carlos Barria

U.S. Army 10th Mountain Division troops listen as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump observes a demonstration with U.S. Army 10th Mountain Division troops, an attack helicopter and artillery as he visits Fort Drum, New York, U.S., August 13, 2018.

A soldier from the U.S. Army's 10th Mountain Division salutes U.S. President Donald Trump during the president's visit to Fort Drum, New York, U.S., August 13, 2018.

U.S. Army 10th Mountain Division soldiers listen as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. Army 10th Mountain Division soldiers listen as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. Army 10th Mountain Division troops listen as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump talks with U.S. Army Major General Walter “Walt” Piatt, the Commanding General of the Army's 10th Mountain Division and Fort Drum as the president observes a demonstration with U.S. Army 10th Mountain Division troops and helicopters at Fort Drum, New York, U.S., August 13, 2018.

U.S. Army 10th Mountain Division soldiers listen as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

A U.S. Army 10th Mountain Division soldier listens as President Donald Trump speaks before signing the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump arrives to address U.S. Army soldiers and sign the National Defense Authorization Act at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump holds up the National Defense Authorization Act after signing it in front of soldiers from the U.S. Army's 10th Mountain Division at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump salutes a U.S. Army soldier as he observes a military demonstration with U.S. Army Major General Walter “Walt” Piatt, the Commanding General of the Army's 10th Mountain Division at Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump talks with a U.S. Army 10th Mountain Division soldier during a military demonstration as he visits Fort Drum, New York, U.S., August 13, 2018.

U.S. President Donald Trump talks with U.S. Army Major General Walter “Walt” Piatt, the Commanding General of the Army's 10th Mountain Division and Fort Drum as the president observes a demonstration with troops and Army helicopters at Fort Drum, New York, U.S., August 13, 2018.

White House Chief of Staff John Kelly deplanes from Air Force One as he arrives with U.S. President Donald Trump at Fort Drum, New York, U.S., August 13, 2018.

White House Press Secretary Sarah Huckabee Sanders watches from beside an Army vehicle as President Donald Trump observes a military demonstration at Fort Drum, New York, U.S., August 13, 2018.