Belgian–Dutch relations refer to interstate relations between the Belgium and the Netherlands. It can be seen as one of the closest international relationships in existence, marked by shared history, culture, institutions and language, extensive people-to-people links, aligned security interests, sporting tournaments and vibrant trade and investment cooperation. Relations were established after Belgium became independent from the United Kingdom of the Netherlands in 1839. Both nations are great allies with cultural similarities and close cooperation between both governments. Dutch, known in Belgium as Flemish, is the most-spoken language in both countries. Approximately 35,000 Belgian nationals live in the Netherlands, while there are around 111,000 Dutch nationals in Belgium.