The problem of Bessarabia was one of the most important issues after the end of the Crimean War. At the suggestion of the Austrian Foreign Minister, Buol, Russia was to cede southern Bessarabia to the Principality of Moldova. During the congress of Paris, the Russian plenipotentiaries proposed an exchange of territories: the fortress of Kars instead southern Bessarabia. British diplomats did not accept such an idea. Due to the fact that the French emperor Napoleon III supported Russia's initiative, Great Britain was in antagonism with its war ally. During the year of 1856 the British-Russian relations were strained due to the problem of southern Bessarabia. The London cabinet sent two ships to the Black Sea to force Russia to abide by the Paris Treaty. After a new conference in Paris, southern Bessarabia was returned to the Principality of Moldova.