Treaty of Trianon
Following the end of World War I, Romania unilaterally declared its sovereignty in 1919 and strengthened its claim with the Treaty of Trianon in 1920. On July 24, 1923, the new Republic of Turkey officially ceded Ada Kaleh to Romania with Articles 25 and 26 of the Treaty of Lausanne; by formally recognizing the related provisions in the Treaty of Trianon.