Unlike

Facebook Inc.

and

Twitter Inc.,

which has permanently banned Mr. Trump, YouTube has provided limited information on its call. Facebook first explained its ban in a personal post by Chief Executive

Mark Zuckerberg

and then referred the matter to its independent Oversight Board. Twitter posted an explanation of its decision and the rules it believed that Mr. Trump violated.

YouTube said in a short statement in January that Mr. Trump’s channel, which has almost 3 million subscribers, was suspended in the wake of the Jan. 6 Capitol riot for violating the platform’s incitement-to-violence policy. The riot, led by Mr. Trump’s supporters, aimed to prevent Congress from certifying President Biden’s victory over Mr. Trump in the November election and resulted in five deaths.

The video service has a three-strikes policy that governs channel suspensions. A single strike, as it imposed on Mr. Trump’s channel, typically results in a one-week suspension. There is no mention in YouTube’s community guidelines of an indefinite suspension as enacted in the former president’s case.

A YouTube spokesman said Wednesday the service prolonged the suspension because of the continuing risk of violence. YouTube’s terms of service give it flexibility to suspend or terminate an account if there is the potential for harm, the spokesman said.

Mr. Trump has frequently criticized social-media companies’ power, saying they tend to suppress conservative views. He has denied claims that he incited people to engage in destructive behavior at the Capitol. In a statement Wednesday, he said, “What Facebook, Twitter, and Google have done is a total disgrace and an embarrassment to our Country.” The companies have rejected allegations their platforms show bias in handling political content.

YouTube Chief Executive

Susan Wojcicki

spoke publicly about the suspension in early March, saying that a recent warning from Capitol Police about a potential attack showed that Mr. Trump’s channel still posed a risk of inciting violence. She said YouTube would lift the suspension when it determines the violence risk has decreased.

“It’s hard for me to say when that’s going to be, but it’s pretty clear right now where we stand,” Ms. Wojcicki said during a virtual event hosted by the Atlantic Council, a think tank.

A YouTube spokesman declined to say who would determine when Mr. Trump’s account would be restored, adding that internal trust and safety teams would continue to evaluate social-media posts, government security alerts and law-enforcement activity.

Ms. Wojcicki, as well as Google Chief Executive

Sundar Pichai

and Chief Legal Officer

Kent Walker

typically weigh in on decisions about YouTube suspensions of high-profile figures such as Mr. Trump, people familiar with the review process said.

The company has avoided detailing employees who are part of its content-review process for safety reasons, these people said. In 2018, a woman armed with a handgun opened fire at YouTube’s headquarters wounding three people and shooting herself months after posting a video where she accused the service of limiting viewer traffic to her content.

YouTube and Ms. Wojcicki, similar to other social-media companies and executives, have fielded criticism from users and lawmakers over content-moderation rules. Free-speech advocates, including those critical of Mr. Trump, have called on YouTube to be more transparent about its rationale for the suspension of the former president and its appeals process.

Kate Ruane, the American Civil Liberties Union’s senior legislative counsel, said that YouTube’s power to freeze the then-president’s account while providing little insight into how or when it might lift the suspension affects the two billion people who use the service each month.

“Any of the big platforms that are operating as gateways to the online public square should be providing the same level of clarity, transparency, consistency and due process as whoever is sitting next to them in a Congressional hearing,” Ms. Ruane said.

The largest U.S.-based social-media companies have typically moved in lockstep on many content issues. After the U.S. Capitol riot, they diverged on how to deal with Mr. Trump.

Snap

chat parent Snap Inc. became the first major platform to announce a permanent ban of Mr. Trump on Jan. 6. At that time, Facebook and Twitter had both locked Mr. Trump’s accounts, but hadn’t yet said whether the moves would be permanent.

A Snap spokeswoman said that the company locked Mr. Trump’s account indefinitely because it “will not amplify voices who incite racial violence and injustice.”

Shortly after, Twitter said it had banned Mr. Trump permanently. Facebook suspended Mr. Trump, and later referred the matter to its Oversight Board, an independent panel that can adjudicate the company’s thorniest content issues. YouTube followed with its suspension.

The introduction of Facebook’s Oversight Board could force its peers to reassess how they deal with content-moderation disputes, Ms. Ruane said. Facebook’s own oversight board Wednesday criticized the company’s lack of transparency over its indefinite suspension of Mr. Trump’s accounts.

—Georgia Wells contributed to this article.

Write to Tripp Mickle at Tripp.Mickle@wsj.com