How many principal partner space agencies manage the core responsibility for the ISS?

Answer

Five

Five principal partner space agencies—NASA, Roscosmos, ESA, JAXA, and CSA—manage the core responsibility for the station’s construction and operation, even though fifteen countries initially signed the Intergovernmental Agreement.

How many principal partner space agencies manage the core responsibility for the ISS?
SpaceISSspace explorationInternational Cooperation