Twitter CEO Jack Dorsey defended his company's ban of President Donald Trump in a lengthy Twitter thread, although he warned that it could set a dangerous precedent.

When Trump incited his followers to storm the U.S. Capitol last week, then continued to tweet potentially ominous messages, Dorsey said the risk to public safety created "extraordinary and untenable circumstance" for the company. Having already briefly suspended Trump's account the day of the Capitol riot, Twitter on Friday banned Trump entirely, then smacked down the president's attempt to tweet using other accounts.

"I believe this was the right decision for Twitter," wrote Dorsey, in one of the thread's plainest-spoken sentences.

But he also acknowledged that actions like the Trump ban amount to a "failure" by Twitter to avoid such situations in the first place, presumably through better and more effective moderation. Extreme measures such as banning Trump highlight the extraordinary power that companies like Twitter can wield, Dorsey wrote — not to mention the collateral damage that such actions can lead to.

While Twitter was grappling with the problem of Trump, Apple, Google and Amazon were moving to effectively shut down the right-wing site Parler by denying it access to app stores and cloud-hosting services, ostensibly because the platform wasn't aggressive enough about removing calls to violence. While declining to criticize his Big Tech counterparts directly, Dorsey suggested that such exercises of power could undermine the "noble purpose and ideals" of the open internet.

The Twitter co-founder, however, had little specific to say about how his platform or other Big Tech companies could avoid such choices in the future.