Belarus’s flag features a white vertical stripe at the hoist decorated with a red ornamental pattern. The rest of the flag is a horizontal red-over-green bicolour, so Belarus is the single canonical answer.
The ornament is based on traditional Belarusian woven designs, especially patterns associated with local textiles and folk costumes. It occupies the flag’s hoist-side strip and is one of the most distinctive features of Belarus’s national symbol. The red upper band covers two-thirds of the main field, while the green lower band covers one-third.
The current flag was introduced in 1995 after a referendum and revised technically in 2012. It is closely related to the flag of the Byelorussian Soviet Socialist Republic, but the modern version removes the Soviet hammer, sickle, and star. Lithuania’s flag is yellow-green-red, Estonia’s is blue-black-white, and Latvia’s is a dark red-white-red design; none has Belarus’s woven ornament.