Armenia’s decision to sign a partial customs alignment with the European Union’s GSP+ framework places the country in direct legal tension with its existing Eurasian Economic Union obligations. The EAEU Treaty explicitly prohibits members from joining other customs arrangements.
Yerevan’s legal team has argued that the agreement is "not a customs union but a trade preferences arrangement" — a distinction Moscow is unlikely to accept on face value.
The political calculation in Yerevan is that the economic benefits of European market access now outweigh the cost of EAEU membership. That calculation may yet prove correct, but it is also the most direct challenge to the EAEU framework in the bloc’s decade of existence.