They do however retain considerable autonomy, and must be unanimous for the EEU to adopt policies or new member states.

In 2010 three core states (Russia, Belarus and Kazakhstan) pursued integration and founded the Eurasian Customs Union and the Single Economic Space.

On 9 October 2014 Armenia signed the treaty and became the newest member state of the EEU on accession on 2 January 2015.

[7][8] Iran joined into a free trade agreement with the EEU in October 2018, following months of negotiations with Russia.

Enlargement of the Union is also subject to the consent of all existing members and the candidate's adoption of the existing body of EEU law and implementing previous decisions made by the Eurasian Commission, which become part of the EEU's regulatory framework.