At the beginning of the 20th century, American, British, Swedish, Russian and Norwegian companies started coal mining. Norway's sovereignty was recognized by the Svalbard Treaty of 1920, with an addition that there would be no military use of Svalbard, and that the other nations retained the rights to their settlements; five years later Norway officially took over the territory. Some historians claim that Norway was given sovereignty as compensation for its Merchant Fleet losses during World War I, when the Norwegian Merchant fleet played an important role supplying the United Kingdom. Only Norwegian and Russian settlements survived World War II.