A supporter welcomes US army convoy as it enters Czech Republic in Harrachov, Sunday, March 29, 2015. The “Dragoon Ride” convoy started last week from Estonia and passed through Latvia, Lithuania and Poland before entering the Czech Republic on a return journey to a German base. (Photo by Petr David Josek/AP Photo)

A US army soldier shows a stryker armored vehicle to children during a stop of their convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

A Czech Republic's soldier hands over beer to a US army soldier upon arrival of their convoy in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

US army soldiers wave to their supporters as they arrive with their convoy in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

A US army soldier helps a kid on top of a stryker armored vehicle during a stop of his convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

A US army soldier shows the inside of a stryker armored vehicle to a kid during a stop of his convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

A US army soldier helps a kid on top of a stryker armored vehicle during a stop of his convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

A supporter shakes hands with a US army soldier as their convoy arrives in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

US army soldiers wave to their supporters as they arrive with their convoy in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

US army soldiers perform maintenance on a stryker armored vehicle during a stop of their convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

US army soldiers arrive with their convoy in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

A US army soldier greets a supporter as a US army convoy arrives in Prague, Czech Republic, Monday, March 30, 2015. (Photo by Petr David Josek/AP Photo)

A US army soldier shows a gun mounted on top of a stryker armored vehicle to children during a stop of his convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)

Children inspect a stryker armored vehicle during a stop of US military convoy in Prague, Czech Republic, Tuesday, March 31, 2015. (Photo by Petr David Josek/AP Photo)