During this period, Iran also assumed a lead role in cultivating closer ties with its neighbours, Turkey, Iraq and Afghanistan. All these countries were pursuing similar domestic modernization plans, and they collectively fostered increased cooperation and formed a loose alliance as a bloc, leading the Western powers to fear what they believed was the creation of an Asiatic Alliance. In the mid to late 1920s, the Turkish and Iranian governments signed a number of frontier and security agreements. Furthermore, when King Amanullah of Afghanistan faced tribal unrest in 1930 which would ultimately lead to his removal from the throne, the Iranian government sent out several planeloads of officers of the Iranian Army to assist the Afghan King quell the revolt. Indeed, the diplomatic steps that were first taken in the 1920s would eventually lead to the adoption of the non-aggression agreement known as the Treaty of Saadabad between the four countries in 1937.