Ambassador-at-large

An ambassador-at-large is a diplomat, a secretary, or a minister of the highest rank who is accredited to represent a country and its people internationally.
Unlike an ambassador-in-residence, who is usually limited to a country or embassy, the ambassador-at-large is entrusted to operate in several usually-neighboring countries, a region or sometimes hold a seat in an international organization like the United Nations and the European Union. In some cases, an ambassador-at-large may even be specifically assigned a role to advise and assist the state or a government in particular issues. Historically, presidents or prime ministers have designated special diplomatic envoys for specific assignments, primarily overseas but sometimes also within the country as an ambassador-at-large.
Honorific title.
According to international protocol, ambassadors and ambassadors-at-large are officially styled and addressed as His/Her Excellency, or Mister/Madam Ambassador. The title may be abbreviated in official correspondence as H.E.
United States ambassadors-at-large.
The US president appointed the first official who specifically bore the title of ambassador-at-large on 12 March 1949 under the authority vested in to deal with specific foreign policy issues, which have been frequently spelled out in their commissions.
Ambassador-at-Large positions in the diplomatic corps of the US State Department include: