An Old Guard takes part in "Flags-In", an annual event where a small American flag is placed in front of more than 240,000 headstones of U.S. service members buried at Arlington National Cemetery in Arlington, Virginia, U.S., May 23, 2019.

Aerobatic pilot John Klatt takes to the skies for practice ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 24, 2019. Picture taken May 24, 2019. REUTERS/Johnny Milano TPX IMAGES OF THE DAY - RC1306972BC0

Vistors pay their final respect for service members in remembrance of Memorial Day at the Arlington National Cemetery, in Arlington, Virginia, U.S. May 27, 2019. REUTERS/Michael A. McCoy - RC1ECFC3A200

The family of Tusla Tuliau pay their respect for service members in remembrance of Memorial Day at the Arlington National Cemetery, in Arlington, Virginia, U.S. May 27, 2019.

A makeshift memorial lays in front of the Vietnam Memorial in observance of Memorial Day in Washington, DC. U.S. May 27, 2019.

Spectators watch as the U.S. Air Force Thunderbirds perform during the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 25, 2019.

A DC-3 flies through New York, ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 23, 2019. The DC-3 was the plane used to transport paratroopers into Normandy during WWII.

A squadron of vintage WWII airplanes used by the GEICO Skytypers accompanies a DC-3 through New York, ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 23, 2019. The DC-3 was the plane used to transport paratroopers into Normandy during WWII. Picture taken May 23, 2019.

A squadron of vintage WWII airplanes used by the GEICO Skytypers accompanies a DC-3 through New York, ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 23, 2019. The DC-3 was the plane used to transport paratroopers into Normandy during WWII. Picture taken May 23, 2019. REUTERS/Johnny Milano - RC1681730DC0

World War II veteran and USMC Sgt Bruce Heilman (ret.), 93, of Richmond, Virginia, awaits the start of the 32nd Annual, and possibly final, Rolling Thunder "Ride for Freedom" during Memorial Day weekend to support veterans and call attention to POWs and MIAs, in Washington,U.S., May 26, 2019.

U.S. Vice President Mike Pence places a flower on the grave of Col. Paul M. Kelly, who was killed in 2007 while deployed Iraq,  in Section 60 at Arlington National Cemetery in Arlington, Virginia, U.S. May 27, 2019 .

Visitors pay their final respect for service members in remembrance of Memorial Day at the Arlington National Cemetery, in Arlington, Virginia, U.S. May 27, 2019.

Veterans of the Gulf War march along Constitution Avenue in National Memorial Day Parade in Washington, D.C. U.S. May 27, 2019.

A Vietnam War veteran pays respect to fallen comrades at the Vietnam Veterans Memorial on the National Mall in Washington, DC. U.S. May 27, 2019.

Operation Desert Storm veterans of the Gulf War parade in a vehicle along Constitution Avenue in National Memorial Day Parade in Washington, DC. U.S. May 27, 2019.

Aerobatic pilot John Klatt takes to the skies for practice ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 24, 2019. Picture taken May 24, 2019.

Vistors pay their final respect for service members in remembrance of Memorial Day at the Arlington National Cemetery, in Arlington, Virginia, U.S. May 27, 2019.

Old Guard soldiers take part in "Flags-In", an annual event where a small American flag is placed in front of more than 240,000 headstones of U.S. service members buried at Arlington National Cemetery in Arlington, Virginia, U.S., May 23, 2019.

U.S. President Donald Trump and first lady Melania Trump stand among the graves during the annual "flags in" ceremonies before Memorial Day as the president visits Arlington National Cemetery in Arlington, Virginia, U.S., May 23, 2019.

A motorcycle rider with American flag fluttering passes crowds during the 32nd Annual, and possibly final, Rolling Thunder "Ride for Freedom" during Memorial Day weekend to support veterans and call attention to POWs and MIAs, in Washington, U.S., May 26, 2019.

USMC Staff Sgt. Tim Chambers (ret.) salutes motorcycle riders as they pass by during the 32nd Annual, and possibly final, Rolling Thunder "Ride for Freedom" during Memorial Day weekend to support veterans and call attention to POWs and MIAs, in Washington, U.S., May 26, 2019.

Air Force Veteran Sabrina Weber of Alabama, hugs her service dog durning a moment of silence in remembrance of Memorial Day at the Arlington National Cemetery, in Arlington, Virginia, U.S. May 27, 2019.

Paula Davis of Maryland, spends time at the grave marker of son PFC Justin Ray Davis, in Section 60 at Arlington National Cemetery in Arlington, Virginia, U.S. May 27, 2019. REUTERS/Michael A. McCoy - RC14C12832F0

Danny Maldonoado of Virginia, spends time at the grave marker of Anthony Ray Yost, in Section 60 at Arlington National Cemetery in Arlington, Virginia, U.S. May 27, 2019.

Thousands of people line Constitution Avenue for the annual National Memorial Day Parade in Washington, DC. May 27, 2019.

Julie Wilusz comforts her husband, Vietnam War veteran "Doc" Steinhilber at the Vietnam Veterans Memorial on the National Mall in Washington, DC. U.S. May 27, 2019. REUTERS/Michael A. McCoy - RC15A7229060

Julie Wilusz comforts her husband, Vietnam War veteran "Doc" Steinhilber at the Vietnam Veterans Memorial on the National Mall in Washington, DC. U.S. May 27, 2019.

Members of the U.S. Army's Golden Knights parachute team perform during the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 25, 2019.

A squadron of vintage WWII airplanes used by the GEICO Skytypers accompanies a DC-3 through New York, ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 23, 2019. The DC-3 was the plane used to transport paratroopers into Normandy during WWII.

A motorcycle rider passes crowds and combat boots, representing the fallen military, during the 32nd Annual, and possibly final, Rolling Thunder "Ride for Freedom" during Memorial Day weekend to support veterans and call attention to POWs and MIAs, in Washington, U.S., May 26, 2019.

Air Force Veteran Sabrina Weber of Alabama and service spends time at the grave marker of a former dog handler in Section 60 at Arlington National Cemetery in Arlington, Virginia, U.S. May 27, 2019.

A visitor pays respect to a fallen service members at the Vietnam Veterans Memorial on the National Mall in Washington, DC. U.S. May 27, 2019.

Operation Desert Storm veterans of the Gulf War parade in a vehicle along Constitution Avenue in National Memorial Day Parade in Washington, DC. U.S. May 27, 2019.

A squadron of vintage WWII airplanes used by the GEICO Skytypers accompanies a DC-3 through New York, ahead of the Bethpage Air Show as part of a Memorial Day event at Jones Beach on Long Island, New York, U.S., May 23, 2019. The DC-3 was the plane used to transport paratroopers into Normandy during WWII.