The object of the espionage might not have involved what we usually think of as national security secrets such as information about U.S. military capabilities and intentions or nuclear warfare, but it was espionage nevertheless. Agents of the Russian government were secretly obtaining information about the American political process and using that information to benefit one political party, the Republicans, and to damage the other political party, the Democrats.
In the world of business, this would be equivalent to obtaining industrial secrets from one business and using them to benefit a business friendly to the hostile power.