Donald Trump is set to ban Americans from downloading the TikTok and WeChat apps to their phones from Sunday. The President of the United States ordered the halt on app store downloads amid an ongoing wrangle over the sale of social networking app TikTok, which Trump has branded a national security threat.

An order from the US government’s Commerce Department outlining the ban is set to be published Friday ahead of Sunday’s block on downloads from Google and Apple’s app stores.

People who already have TikTok and WeChat on their phones will not be prevented from using them, or forced to remove them, but they will be unable to upgrade the apps as new versions of them become available. That will make them significantly harder to use over time.

Trump could still rescind the ban if TikTok – which is owed by Chinese social media giant ByteDance – is sold to a US owner in the coming days, with talks about a sale to American owners ongoing. ByteDance is said to want to turn TikTok into a new company – TikTok Global – with US corporation Oracle, although Trump has yet to comment on that proposal.

TikTok – which lets users share short video clips of themselves featuring music and special effects – is hugely popular among young Americans, with 100 million people in the United States using it regularly. Trump has claimed American users data is being spyed on by Chinese government officials, although both the Chinese government and ByteDance deny those claims.

WeChat is China’s most popular social media messaging app, and is used by over 1 billion of the countries 1.4billion people.

It combines the features of apps including Instagram, WhatsApp and Venmo. China’s communist government has come under fire for censoring and removing content from the app which casts its policies in a damaging light.

It has around 19 million US users, and is popular among Chinese-Americans, Chinese students in the US, and US businesspeople with work interests in China.