The chairman of the Federal Communications Commission told senators Thursday he waited several months before correcting his claim about a suspected cyberattack during his agency’s “net neutrality” debate because doing so may have hindered an ongoing investigation.

The FCC’s online public comment portal crashed in May 2017 as the agency was considering its controversial decision to repeal Obama-era “net neutrality” rules. The FCC was quick to assert that a coordinated cyberattack had prevented people from registering their opinions about the change.