Twitter will no longer allow political advertising on its platform out of concern for the spread of misinformation, founder Jack Dorsey announced Wednesday.

“Why? A few reasons ... ” Dorsey began a long string of tweets.

“While internet advertising is incredibly powerful and very effective for commercial advertisers, that power brings significant risks to politics, where it can be used to influence votes to affect the lives of millions,” Dorsey said.

Twitter will take additional steps to quell foreign-made bots on the platform, which played a part in the Russia-backed 2016 disinformation campaign.

Dorsey continued: “Internet political ads present entirely new challenges to civic discourse: machine learning-based optimization of messaging and micro-targeting, unchecked misleading information, and deep fakes. All at increasing velocity, sophistication, and overwhelming scale.”

The new policy is a stark contrast to that of Facebook, which is grappling with increasingly vocal critics of its hands-off political advertising policy ― the site refuses to fact-check claims made by politicians except in extreme cases. Facebook has refused to pull a Trump campaign ad that baselessly accuses former Vice President Joe Biden of promising $1 billion to Ukraine to benefit his son.

Founder and CEO Mark Zuckerberg also did little to clear up questions about Facebook’s approach to stifling misinformation during a congressional hearing earlier this month, where he was not able to tell Rep. Alexandria Ocasio-Cortez definitively whether a hypothetical ad she described would be permitted on the platform.

Dorsey appeared to take multiple swipes at his tech-giant counterpart.

“[I]t’s not credible for us to say: ‘We’re working hard to stop people from gaming our systems to spread misleading info, buuut if someone pays us to target and force people to see their political ad … well ... they can say whatever they want!’” Dorsey wrote in one tweet. The Facebook founder claimed in a recent letter to employees that the company is “working hard” to “give users more context on the content they see, demote violating content, and more.”