A new story came out today about Russia potentially preventing the US from using the ISS. One of the claims made was "The Russian segment [of ISS] can exist independently from the American one. The U.S. one cannot.": "The Russian segment [of ISS] can exist independently from the American one. The U.S. one cannot."
Leaving aside all the political considerations of whether any of this is a good idea, is this claim true? Can the US side not survive on it's own? Why was such a design made so that it couldn't survive but the Russian side could?