In the summer of 2020, in the midst of re-election and looking for new ways to punish China, President Donald J. Trump threatened to cut off TikTok from the phones of millions of Americans unless its parent company agreed to sell all of its US operations. to American owners. The effort collapsed.

Now, more than two years later, after lengthy studies of how Chinese authorities could use the app for everything from surveillance to information operations, the Biden administration is trying a startlingly similar move. It’s better organized, monitored by lawyers, and coordinated with new bills in Congress that appear to have considerable bipartisan support.

Yet protecting TikTok from Chinese exploitation — as a tool for Chinese authorities to monitor the likes and whereabouts of Americans, as an entry point into phones that contain their entire lives, and as a means of disseminating misinformation – proves to be more difficult than that. looks.

Tensions around the app will come to a head on Thursday, when Singapore-based TikTok chief executive Shou Chew testifies before the House Energy and Commerce Committee, a hearing that will give Democrats and Republicans a rare chance to speak directly. their suspicions. to the company. On Tuesday, Mr Chew posted a TikTok from the company’s main account, saying “some politicians” are trying to take the app down from 150 million users in the US, including small businesses.

But after two years of negotiations with TikTok over putting new protections in place, it’s unclear if the company can do anything short of handing over the entire operation to the Americans, which will satisfy people’s concerns. US intelligence agencies. The Justice Department’s No. 2 official and others have effectively rejected proposals from TikTok’s parent company, ByteDance, to address concerns.

Any decision to remove the app, either banning it from 150 million users in the United States or blocking further downloads, would be politically burdensome for Mr Biden. No one has summed up the political dilemma better than Gina Raimondo, the Secretary of Commerce, who is at the center of new export controls imposed on high-tech products to China.

“The politician in me thinks you’re literally going to lose every voter under 35, forever,” she recently told Bloomberg News.

Raimondo and other officials are quick to add that bad policy is no reason to waive a total ban if the threat to National Security warrants it. The issue is made more complex by the fact that some of the world’s biggest news organizations, including the New York Times, now have TikTok accounts, which means shutting down the app could appear to stop the spread of factual news. to counter Chinese disinformation.

“It’s largely a game of chicken,” said James A. Lewis, who directs the cyber threats program at the Center for Strategic and International Studies. But he thinks Mr. Biden has a much better chance of succeeding than his predecessor.

“Different from the Trump administration, I think this administration has a chance to win – attitudes have changed towards China,” he said. Several new bills that would in different ways give the president explicit new authority to shut down TikTok have received bipartisan support. They are propelled by the intelligence community’s conclusion, contained in the Global Threat Assessment submitted to Congress, that China remains the “broadest, most active, and most persistent” cyber threat to the country.

Yet, so far, the threat from TikTok is largely theoretical.

There have been a handful of abuse cases, including efforts to geotag journalists who have published leaked information about the company. But the administration has not presented full, declassified evidence of a systemic effort to use the app to advance the Chinese government’s collection efforts.

That hasn’t stopped nearly 30 states from banning TikTok from official government or contractor phones, and federal employees are also required to remove it, but not from their personal devices.

There are three clear areas of concern. The first is where TikTok stores its users’ data in the United States. Until recently, much of it was on servers run by ByteDance in Singapore and Virginia, which many feared would allow China to demand that TikTok hand over user data under national security laws. Beijing. This year, TikTok tried to preempt that argument, saying it would delete its US users’ data from ByteDance servers and move it to servers run by Oracle, a US cloud computing company.

Then comes the hardest question – who writes the algorithm, the code that is TikTok’s secret sauce. This code evaluates a user’s choices and uses them to select more material to feed the user – a favorite dance routine, or perhaps an interesting news item. The algorithms were written in China, by Chinese engineers who have honed the art of giving users what they want to see. The concern, Matt Perault and Samm Sacks recently wrote on the Lawfare blog, is that “TikTok could unilaterally decide to prioritize content that threatens or destabilizes the United States.” Again, that hasn’t happened yet, at least not via TikTok.

And finally, there’s the question of whether an app whose algorithm few understand could be a gateway for outsiders, including China’s Ministry of State Security, to access Americans’ phones – to find out not their dance preferences, but the vast treasure trove of data they carry in their hip pockets.

In November, Christopher A. Wray, the director of the FBI, warned that the Chinese government could use TikTok’s algorithm for “influence operations”. Gen. Paul M. Nakasone, head of US Cyber ​​Command and director of the National Security Agency, echoed those concerns this month, saying “it’s not just the fact that you can influence something. , but you can also disable the message”. also when you have such a large population of listeners.

TikTok has sought to address misinformation issues with a long list of updated policies for video moderation, including new restrictions and labeling rules for deepfakes – highly realistic fake videos made with artificial intelligence. TikTok, for example, will not allow deepfakes of private figures and will ban deepfakes of public figures if the content is used for endorsements. He also offered more details on how he will “protect civic and electoral integrity.”

A TikTok spokeswoman did not respond to a request for comment.

The fight over enforcement had already become a thorny legal issue by the time Mr Biden inherited it from Mr Trump in 2021.

Federal courts had ruled that Mr. Trump lacked the power to execute his proposed ban on the app from Apple and Google’s app stores, removing the crucial leverage that the House Blanche had used to get ByteDance to consider selling TikTok.

Mr. Biden issued an executive order in June 2021 rescinding Mr. Trump’s ban threat. He left in place the order that asked ByteDance to surrender the application. But staff members of a group of federal agencies that review foreign businesses in America, the Committee on Foreign Investment in the United States, were considering a third option: negotiate a deal with TikTok that would address national security concerns. but would not force ByteDance to sell the app.

According to its latest proposal, TikTok would not only store US user data on Oracle servers in the US; the cloud company is also said to monitor its content recommendation algorithm – which TikTok says is a safeguard against the app being used to spread propaganda. And the entity governing enforcement in the United States would be overseen by a government-approved three-person board.

But this proposal did not satisfy the hawks in Washington. Some in the administration — including Lisa O. Monaco, the deputy attorney general — worried that his terms weren’t strict enough. The administration has also faced mounting pressure from lawmakers who have said the app should be banned altogether.

Now the Biden administration is pursuing a new strategy.

Publicly, he backed legislation earlier this month from a bipartisan group of senators that would give the Commerce Department clearer power to ban the app, potentially restoring government influence over ByteDance. Privately, administration officials told TikTok they want its Chinese ownership to sell the app or face a possible ban. If the legislation were passed, it would significantly strengthen the administration’s hand in forcing a sale.

Peter Harrell, a lawyer and former senior director of international economics and competitiveness at the National Security Council, said the proposed legislation is “significant because, as the United States deals with TikTok and other Chinese apps, they need clear legal authorities to regulate and constrain”. actions” that do not exist in the current law.

A White House spokeswoman declined to comment beyond her current support for the legislation.

At times, TikTok undermined its own arguments. It said it would not pass information about its users to the Chinese government – ​​although China’s national security law clearly requires it to do so if the country’s intelligence services order its Chinese employees to do so. .

When Forbes reported in October that a China-based team at ByteDance planned to use TikTok to monitor the locations of certain Americans, TikTok’s communications team responded on Twitter that the publication’s work lacked “both rigor and journalistic integrity”. He also said that TikTok had “never been used to ‘target’” American politicians or journalists.

Two months later, ByteDance admitted that four of its employees, including two based in China, had gained access to the IP addresses and other data of two journalists, as well as some people connected to the journalists through their TikTok accounts. Employees were trying to determine if the individuals had met with ByteDance employees, so they could attempt to discern the source of the leaks to reporters.

TikTok dismissed the case as an anomaly and fired the employees. He said he has systems in place to prevent a recurrence. And no doubt, corporate America has had similar insider incidents of privacy breaches.

But in the current atmosphere in Washington, especially after a Chinese surveillance balloon crashed across the United States in January, any evidence of Chinese surveillance fuels a deep, bipartisan desire to crack down on the entry points of China to US networks. And of those, there is none bigger – or more influential – than TikTok, which is why the path the administration will take over the next few months could set a precedent that goes well. beyond the immediate fate of TikTok.

Julian Barnes contributed reporting from Washington.