NEW YORK (AP) — U.S. Secretary of State Mike Pompeo on Wednesday called for a big expansion of U.S. government curbs on Chinese technology, saying that it wants to see “untrusted Chinese apps" pulled from the Google and Apple app stores.

Outside experts called Pompeo's proposal vague and possibly illegal.

Pompeo called out popular video app TikTok and the messaging app WeChat, which people in the U.S. use to communicate with others in the U.S. and China, as “significant threats to the personal data of American citizens, not to mention tools for CCP content censorship.” CCP refers to the Chinese Communist Party.

The U.S. government has already been cracking down on Chinese technology companies. For instance, it has long singled out telecom equipment provider Huawei, encouraging allies not to use its equipment in their high-speed 5G wireless networks and banning U.S. telecom companies from using government funds for equipment and services from Huawei and ZTE, another Chinese telecom equipment provider.

Citing national security concerns, it has also barred Google from providing its Android apps such as Google Maps for Huawei phones. The Federal Communications Commission is considering barring operations of Chinese telecom companies China Telecom and China Unicom, which provide services in the U.S., due to national-security concerns.

President Donald Trump has also threatened to ban TikTok, although the legal basis for such a move remains uncertain.

“It’s a PR stunt. No specifics. It’s an objective,” George Washington University professor Susan Ariel Aaronson said by email.

Eurasia Group analyst Paul Triolo said the U.S. government is trying to push its allies and companies to stop using Chinese gear and software “at all levels of their communications networks, from the internet backbone to app stores.” That includes calling for companies to yank their apps from Huawei's app store, which advertises that it contains apps from European and U.S. companies like travel service Booking and Amazon.

The legal authority for the administration to take action against apps and app stores is unclear, Triolo write in a research note. The State Department did not immediately a question seeking information about the legal authority the administration could use to justify such measures.

The initiative is meant to force countries and companies to choose sides between the U.S. and China, Triolo said. He expects many companies and governments to resist.