The ITU (A UN agency) is a membership organization that coordinates
amongst the membership to attempt to get everyone to agree on band
usage, but has no legal force in any country.
So most member countries agree on most usage for most of the spectrum,
but exceptions occur everywhere per the best interest of individual
countries.
Often, for example, grandfathered use of spectrum dictates usage in one
country v. compliance to international agreements in most others.
At higher frequencies, esp. where ground/sea level use is concerned it
doesn't matter much as they are line-of-sight and shorter range.