TikTok CEO Kevin Mayer resigned Wednesday amid an impending ban imposed by the Trump administration that would restrict the video app in the United States beginning in mid-September.

Mayer, a former Disney executive, was in the role for only three months.

In a letter to employees Wednesday, Mayer said that “the political environment has sharply changed” since he accepted the role in May and that a new resolution for the company is expected soon.

“I understand that the role that I signed up for — including running TikTok globally — will look very different as a result of the US Administration’s action to push for a sell off of the US business,” he wrote in a letter obtained by The Washington Post.

The Financial Times earlier reported Mayer’s departure.

President Trump issued an executive order earlier this month announcing that TikTok would be banned in the United States beginning the week of Sept. 20 because of national security concerns stemming from the company’s Chinese ownership.

A week later, Trump issued another order requiring TikTok’s owner, ByteDance, to divest an acquisition that created TikTok’s popularity in the United States.

TikTok sued the administration Monday, alleging that it was not given due process and asserting that it is not a national security threat.

Mayer’s departure throws more uncertainty into the mix for the embattled TikTok, which has been a high-profile example of escalating tensions between the United States and China. Mayer’s hiring was a key move in TikTok’s public relations strategy to appeal to U.S. regulators as an American-friendly company.

The company, which has about 1,500 employees in the United States, has denied that it’s a security threat. It says it keeps U.S. customer data stored only within the country and Singapore, and does not share it with the Chinese government.

TikTok’s popularity has surged in the United States over the past year. The company has said it had 91.9 million monthly active users in the country in June, up from 26.7 million in February 2019. On a quarterly basis, the company says that 100 million in the United States use the app.

TikTok spokesperson Hilary McQuaide said General Manager Vanessa Pappas will serve as interim head of TikTok.

“We appreciate that the political dynamics of the last few months have significantly changed what the scope of Kevin’s role would be going forward, and fully respect his decision,” McQuaide said in a statement.

Microsoft has said it is in talks to purchase TikTok and expects to conclude negotiations by Sept. 15.

Mayer said in his email that he decided to join the company because of its uniqueness and its ability to alter the Internet. But that has changed.

“Against this backdrop, and as we expect to reach a resolution very soon, it is with a heavy heart that I wanted to let you all know that I have decided to leave the company,” he wrote. “I want to be clear that this decision has nothing to do with the company, what I see for our future, or the belief I have in what we are building.“

He added that any structural changes shouldn’t affect users.

“The platform will continue to provide our global community an amazing and integrated experience as it does today,” he said.