> if it's a clear threat, the government should have no problem explaining what exactly the threat is. It seems plausible to me that there is a national security threat, but i'm bothered by the government being able to invoke national security as a set of magic words that excuse them from explaining anything further.

It's pretty obvious: TikTok could be a potent propaganda tool, and in a time of increasing geopolitical tensions, you don't hand an adversary nation potential weapons like that. Also, Chinese intelligence is interested in collecting information on Americans (and others) that an app like TikTok could provide. For instance:

https://www.nytimes.com/2018/12/11/us/politics/trump-china-t...

> WASHINGTON — The cyberattack on the Marriott hotel chain that collected personal details of roughly 500 million guests was part of a Chinese intelligence-gathering effort that also hacked health insurers and the security clearance files of millions more Americans, according to two people briefed on the investigation....

> Such information is exactly what the Chinese use to root out spies, recruit intelligence agents and build a rich repository of Americans’ personal data for future targeting. With those details and more that were stolen from insurers like Anthem, the Marriott data adds another critical element to the intelligence profile: travel habits.

> James A. Lewis, a cybersecurity expert at the Center for Strategic Studies in Washington, said the Chinese have collected “huge pots of data” to feed a Ministry of State Security database seeking to identify American spies — and the Chinese people talking to them.

> “Big data is the new wave for counterintelligence,” Mr. Lewis said.

The thing is US has its own TikToks: if US bans TikTok, CCP will use its influence to undermine FB, WhatsApp, IG, Snapchat, etc. CCP is pretty much saying: "we know you're spying on the entire world and we want to do the same; if you torpedo our secret submarine, we'll do the same to yours."

They’ve already blocked those in China, Gmail, Google, FB etc. The insidious thing with WeChat is politically sensitive items are reviewed then blocked and use of the app trains their blocking heuristics.

CCP's influence doesn't end at China's borders.

The Matrix is all around us, in the food we eat, on the television, inside this very room...