Bulgaria’s Deputy Prime Minister and Minister of Foreign Affairs Mariya Gabriel validated a postage stamp dedicated to the 120th anniversary of the establishment of diplomatic relations between Bulgaria and the United States. Bulgaria’s Minister of Transport and Communications Georgi Gvozdeikov and the United States Ambassador to Bulgaria Kenneth Merten also attended the ceremony.

The stamp features the letter of credence, which was presented in 1903 to King Ferdinand by the first Minister Plenipotentiary of the Unites States in Bulgaria, John Jackson. The letter of credence was signed by the American President Theodore Roosevelt. Bulgaria and the United States established diplomatic relations in 1903. Bulgaria's independence, declared on 22 September, 1908, was recognized by the United States on 3 May, 1909. On December 22, 1914, Stefan Panaretov presented his credentials as Bulgaria’s first Minister Plenipotentiary to the United States. He remained in this post until 1925.