FBI agents visited the homes of several employees of Kaspersky Lab, a Russia-based cyber security firm, Tuesday to learn more about "the company's operations as part of a counter-intelligence inquiry," reports NBC's Ken Dilanian and Tom Winter, citing multiple sources familiar with the matter.

The agents reportedly told the employees that they weren't in trouble, and that the FBI was only investigating how the company works, "including the extent of which the U.S. operations ultimately report to Moscow."

There is no indication that the investigation is linked to Special Prosecutor Robert Mueller's Russia investigation, Dilanian and Winter explain, noting that Kaspersky "has long been of interest to the U.S. government," as the company's software is widely used in the U.S. and its owner, Eugene Kaspersky, has "close ties to some Russian intelligence figures."