Comment by dvogel

You've added something that was not in the article. The IP address was not necessarily in the GRU HQ. The IP was in Moscow. The IP allowed the agent to be identified. That might mean the IP was in the GRU HQ but not necessarily. Once the agent was identified, they knew (possibly based on other intel collection) that he works out of (has as a "home" office) the GRU HQ.