Diplomacy was to take centre stage as the country began to take more serious steps to modernize following Ras Tefferi's growing access to power as Regent from 1916 and then as Emperor Haile Selassie from 1930. This was symbolized by Ethiopia's growing adoption of western life styles and development, with more and more diplomatic missions being sent abroad and equally numerous foreign delegations being received in Addis Ababa. Ras Tefferi's coronation as Haile Selassie in 1930 attracted visitors from all round the world.
While Ethiopia's entry to the League of Nations in 1923 was perhaps one of the most important milestones in Ethiopia's diplomatic history, as important in public relations terms was Ras Tefferi's visit the next year to Jerusalem, Egypt, France, Italy, Belgium, Luxembourg, Switzerland, Sweden, Great Britain, and Greece. Membership of the League of Nations was considered important in ensuring the acceptance of Ethiopia's independence, but the League's member states failed to make any serious effort to stop Fascist Italy's invasion in 1935. Haile Selassie himself spoke to the League of Nations: "I ask the fifty-two nations, who have given the Ethiopian people a promise to help them in their resistance to the aggressor, what are they willing to do for Ethiopia? And the great Powers who have promised the guarantee of collective security to small States on whom weighs the threat that they may one day suffer the fate of Ethiopia, I ask what measures do you intend to take? Representatives of the World I have come to Geneva to discharge in your midst the most painful of the duties of the head of a State. What reply shall I have to take back to my people?" The League's failure left a lasting scar on the history of the concept of collective international security and justice.
However, it did not destroy Ethiopia's belief in the concept of collective security. Indeed, the effect was rather to make the country more determined than ever to ensure that in the future such concepts should be made to work. Ethiopia became a founding member of the United Nations and it has subsequently played a significant role in all subsequent efforts to make sure that the success of collective security. Ethiopia's participation in the United Nations operations in Korea and then in Congo, as well as later in Rwanda, Burundi, Liberia and Sudan are a testament to the country's unyielding commitment to collective security.