ABO

ABO (access, basing, and overflight) is a military-legal doctrine governing the permissions a host nation grants to allied or foreign forces: physical access to territory or ports, use of military bases and installations, and permission for military aircraft to transit airspace. ABO rights are typically established through Status of Forces Agreements (SOFAs) or dedicated bilateral defence agreements, and their grant or denial is a sovereign decision that sits with the host government.

The ABO concept became the central mechanism of the NATO fracture during the Iran war. A leaked Pentagon email on 24 April 2026 proposed penalising allies who had refused ABO rights during the Iran campaign, specifically naming Spain (Naval Station Rota and Morón Air Base), and implicating France (Keir Starmer and Emmanuel Macron were also referenced for refusing Hormuz blockade participation). The email proposed suspending these allies from prestigious NATO positions and reassessing US diplomatic support for the Falkland Islands.

ABO refusals are legally significant because they expose the gap between alliance solidarity, which is political, and operational cooperation, which requires specific contractual and sovereign acts. An ally can be politically supportive of a campaign while legally declining to grant ABO rights under its domestic constitutional constraints or treaty interpretation, which is precisely the position Spain, France, and the UK have adopted.