 The United Kingdom relies on "de facto" arguments of possession by prescription in relation to the southern part of the isthmus, as there has been "continuous possession [of the isthmus] over a long period".On December 2, 1987, in a , as well as in several EU acts, the UK has acknowledged that Spain disputes the sovereignty of the isthmus ("The ... arrangements ... are understood to be without prejudice to the respective legal positions of Spain and the United Kingdom with regard to the dispute over sovereignty over the territory in which the airport is situated.