A defense attaché (often abbreviated DATT) is a commissioned officer of the sending state's armed forces accredited to a host country as a member of the diplomatic staff of an embassy. The position is recognized under the Vienna Convention on Diplomatic Relations (1961), which in Article 7 permits sending states to freely appoint members of the mission and specifies in the same article that the receiving state may require the names of military, naval, or air attachés to be submitted in advance for approval.
Defense attachés perform several overt functions:
- Representation: serving as the senior uniformed representative of their country's ministry of defense at the embassy, attending official ceremonies, and advising the ambassador on military matters.
- Liaison: maintaining working relationships with the host nation's armed forces, ministry of defense, and other accredited attachés.
- Reporting: collecting and analyzing openly available information on the host state's military posture, doctrine, procurement, and security environment for transmission to their own defense establishment.
- Security cooperation: facilitating arms sales, joint exercises, training exchanges, and visits by senior defense officials.
Larger embassies typically host a Defense Attaché Office (DAO) headed by a senior officer (often a colonel, captain, or flag officer), with subordinate service attachés representing the army, navy, and air force separately. Smaller posts may consolidate these roles into one billet, sometimes covering multiple accreditations across neighboring countries.
Defense attachés enjoy full diplomatic immunity under the Vienna Convention. While their work is overt, attachés can be declared persona non grata and expelled, as occurred in numerous reciprocal expulsions between Russia and Western states following the 2018 Skripal poisoning and the 2022 invasion of Ukraine. Their function is distinct from clandestine military intelligence officers operating under diplomatic cover.
Example
In April 2022, several European states expelled Russian defense attachés alongside other diplomats in response to the invasion of Ukraine and reports of civilian killings in Bucha.