Russia's space agency, Roscosmos, and the US' NASA have both released statements revealing their intention to work together on a base that'll orbit the moon. The countries share a "common vision for human exploration," which is why they're working together.
It appears they'll jointly work on the Deep Space Gateway project. That initiative involves building a base in lunar orbit starting in the mid-2020s.
Roscosmos is also going to work on international standards for the station and other projects, specifically for docking ports and life support systems.
More international partners may end up joining the lunar base project.