Peiter Zatko—better known by his hacker handle, Mudge—joined the social network in the newly created role of head of security, reporting to CEO Jack Dorsey.

Zatko most recently oversaw security at electronic payments platform Stripe, following stints at Google and the Defense Advanced Research and Projects Agency.

He said in a tweet Monday, “Looks like the cat is out of the bag. I’m very excited to be joining the executive team at Twitter. I truly believe in the mission of (equitably) serving the public conversation. I will do my best.”

Zatko said in an interview with Reuters that he will examine “information security, site integrity, physical security, platform integrity—which starts to touch on abuse and manipulation of the platform—and engineering.”

He added, “They are willing to take some risks. With the challenges of algorithms and algorithmic bias, they are not standing by and waiting until someone else solves the problem.”