> The nautical mile is not an SI unit, so it is not defined by a single organization
"In 1929 the International Hydrographic Bureau obtained an agreement from a large number of countries to adopt a value of 1852 metres for the nautical mile, the unit thus defined to be called the International Nautical Mile."
But there was no treaty or anything with a fancy ceremony, just a 'handshake', and so it was up to each country to adopt it with a domestic law or regulation, which (e.g.) the US did in 1954:
Previously in the US it was 1853.25 m (because the US is actually metric "officially": all of its customary units (ft, oz) are defined in terms of metric equivalents):