North Atlantic Treaty Organization
| DATE | NATION | 
| 24 august 1949 | United Kingdom | 
|  | France | 
|  | Belgium | 
|  | Netherlands | 
|  | Luxemburg | 
|  | Norway | 
|  | Denmark | 
|  | Iceland | 
|  | Portugal | 
|  | Italy | 
|  | U.S.A. | 
|  | Canada | 
| 18 february 1952 | Greece | 
|  | Turkey | 
| 5 may 1955 | Germany | 
| 30 may 1982 | Spain | 
| 12 march 1999 | Poland | 
|  | Czech Republic | 
|  | Hungary | 
| 1 may 2004 | Bulgaria | 
|  | Estonia | 
|  | Latvia | 
|  | Lithuania | 
|  | Romania | 
|  | Slovenia | 
|  | Slovaquie | 
| 3 april 2008 | Albania | 
|  | Croatia | 
| 5 june 2017 | Montenegro | 
| 7 february 2019 | North Macedonia | 
| 4 april 2023 | Finland | 
| 24 october 2023 | Sweden | 
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