Arístegui was from 2015 and until February 12, Spain's deputy permanent ambassador to the EU, a position for which Raúl Fuentes Milani, one of the members of the Spanish negotiating team for Brexit, has been appointed.
That same day, diplomat José Luis de la Peña Vela was dismissed as ambassador to Slovenia, a position that Juan Arístegui will now occupy.
Arístegui, a law graduate and diplomat since 1990, has had a career closely linked to Europe. He has been a technical advisor in the cabinet of the Minister of Foreign Affairs and has been assigned to Spanish diplomatic representations in Finland and Turkey.
He has also been deputy director general for General Affairs in the State Secretariat for European Affairs, coordinator of COREPER, in the Permanent Representation of Spain to the European Union and deputy director general for Social Affairs in the General Directorate for Consular and Migration Affairs, and Europe Eastern and Central Asia. In September 2011 he was appointed director of the cabinet of the secretary of state for the European Union.