Russia supplies the thrusters and the fuel for said thrusters to keep the ISS in orbit. Periodically the thrusters have to be replaced and the ISS boosted back into orbit. Well, Russia just announced that it would no longer supply those and will build a space station with China.
It is unlikely we will be able to design and manufacture the thrusters within the two year time frame they are needed and thus the ISS will come down in the next week couple of years instead of 2031 as planned.
