“This is not a small thing — this is like a country’s flag,” says Jose Luis Sanchez Ayuso, the president of Atletico fan group Senales de Humo (Smoke Signals).

Despite efforts by the authorities to stop people from flying the red-and-white flag adopted by the opposition, Belarusians are finding unique ways to show their solidarity.

A sea of red, white, and blue for the 4th of July—you can take a stroll through America’s past with a patriotic showcase in ...