Guarantee! The formula coined in 1814 rings ironical to-day. Belgium was guaranteed [Treaty of London, 1839] in order to secure the stability of Europe, yet on account of that guarantee Great Britain and Germany, two of the greatest sovereign units in the European complexus, are at this moment engaged in a life-and-death struggle. Germany violated the Belgian guarantee deliberately in her attempt to destroy the European system by war. The effect of the guarantee may still prove momentous: it has drawn us into the war, and our intervention may turn the scale. Yet even if the Allies are victorious, and the new Europe is fashioned by them after their own hearts and not by Germany after hers, this will not save the credit of the guarantee itself. Germany may be punished for her work, but the work cannot be undone. Europe must drink the cup of war to the dregs – the pain, the hate, the waste, the pure evil that is not diminished one drop by cause or consequence. The guarantee was invented to avert that catastrophe from Europe. The catastrophe has happened and the invention is bankrupt.
See The question of a general guarantee in Mark Jarrett, The Congress of Vienna and Its Legacy, IB Tauris, 2013.
Ukrainian sovereignty would be guaranteed by NATO if Ukraine were a member of NATO, but see 1994 Budapest Memorandum.
Nationality and the War, Dent, 1915