On July 19 local time, Spain defeated Argentina in the World Cup final and won the championship.
According to Reuters and The Guardian, boos could be heard from the stands during the award ceremony held that day as U.S. President Donald Trump and FIFA President Sepp Blatter entered the stage. The boos only stopped when the two awarded medals to players and coaches.

Infantino and Trump. Reuters
According to reports, Trump arrived at the New Jersey Stadium in New York by helicopter. Subsequently, he sat with Ignanti and watched the final game through bulletproof glass. After the U.S. national anthem was played, Trump's figure appeared briefly on the stadium's large screen. There were scattered boos from the crowd.
However, after Spain won the championship, when Trump and Inzaghi entered to receive the award, there was a lot of booing in the stadium. The White House press corps reported that the noise level at the scene had previously been around 78 decibels, but rose to 84 decibels after Trump entered the stage.
Reuters reported that American team player Barlogon was sent off with a red card during the match against the Bosnia team. Trump called Gianni Infantino to request a review of the red-card suspension. This has made Trump the center of the biggest controversy in this World Cup.
During the award ceremony, after presenting the championship trophy to the Spanish team, Trump stood next to the podium and celebrated with the players. Infantino tried to pull him away.
The Guardian states that this is similar to the situation during the final of the FIFA Club World Cup last summer. At that time, after presenting the award to the champion Chelsea team, Trump remained on the stage and celebrated with the players, which confused the players.