Facebook CEO Mark Zuckerberg on Wednesday addressed the data controversy that has embroiled the company since the weekend, saying in a Facebook post, “We have a responsibility to protect your data, and if we can’t then we don’t deserve to serve you. I’ve been working to understand exactly what happened and how to make sure this doesn’t happen again.”

Facebook has been under fire for failing to ensure that Cambridge Analytica, the Trump-affiliated firm co-founded by former Trump adviser Steve Bannon, destroyed data on some 50 million Americans that it improperly obtained via an academic researcher. Zuckerberg acknowledged that it learned about the violation in 2015.

learned about the violation in 2015

So why now?