Simeon Saxe-Coburg-Gotha was his country's prime minister 2001-2005. Between 1943 and 1946, he was the (minor) monarch of the same country. Which nation are we talking about?

Explanation

Simeon is the son of Tsar Boris III and Tsarita Giovanna di Savoia and is related to various European royalty, including Queen Elizabeth II. Following his birth, Boris III sent an air force officer to the River Jordan to obtain water for Simeon's baptism in the Orthodox faith. He became Tsar on 28 August 1943 on the death of his father, who had just returned to Bulgaria from a meeting with Adolf Hitler but as he was only six years old, three regents were appointed.