| Country | Action | Action Date | Effective Date |
|---|---|---|---|
| BELGIUM | Accession | 03/07/1953 | |
| FRANCE | Signature | 10/11/1952 | |
| ITALY | Signature | 10/11/1952 | |
| NETHERLANDS THE | Accession | 23/06/1953 | |
| PORTUGAL | Accession | 18/03/1953 | |
| SPAIN | Signature | 10/11/1952 | |
| SWEDEN | Accession | 27/04/1953 | |
| UNITED KINGDOM | Signature | 10/11/1952 | |
| UNITED STATES OF AMERICA | Accession | 08/07/1953 |