An attaché is a member of a diplomatic mission who is seconded from a sending state's ministry or armed forces to provide expert reporting and liaison on a defined subject area. Unlike generalist career diplomats, attachés are typically subject-matter specialists: a defense attaché is usually a serving military officer, an agricultural attaché may come from the ministry of agriculture, and a cultural attaché is often drawn from cultural or educational agencies.
Under the Vienna Convention on Diplomatic Relations (1961), attachés are listed among the diplomatic staff of a mission and enjoy the privileges and immunities accorded to diplomatic agents, provided they are formally notified to and accepted by the receiving state. Military, naval, and air attachés receive special treatment: Article 7 of the Convention allows the receiving state to require their names to be submitted in advance for approval.
Common functions of attachés include:
- Reporting on developments in their sector back to their home ministry.
- Liaison with counterpart institutions in the host state (e.g., a defense attaché working with the host's armed forces).
- Negotiation support on technical files where embassy generalists lack expertise.
- Representation at specialized conferences, trade fairs, or military exercises.
The rank of attaché also exists as the most junior diplomatic rank in many foreign services, held by entry-level career officers before promotion to third secretary. This dual usage — both a junior generalist rank and a senior specialist title — can cause confusion. In practice, the qualifier ("defense attaché," "press attaché") signals the specialist meaning, while an unqualified "attaché" on a diplomatic list usually denotes the junior rank.
Example
In 2018, the United Kingdom expelled 23 Russian diplomats, including several intelligence officers operating under attaché cover, following the Salisbury poisoning of Sergei Skripal.