Sens. Joe Donnelly, D-Ind., and Dean Heller, R-Nev., have asked credit monitoring service Equifax to explain how it is protecting the 1.3 million active-duty servicemembers affected by a massive data breach this year.

The senators sent Equifax CEO Richard F. Smith a letter on Tuesday asking the company to share its plan to help members of the military who may not be in a position to respond to the issue.