American tech giants such as Alphabet Inc.’s Google are considering alternatives to Hong Kong as a global data hub after U.S. national security officials upended plans for a trans-Pacific internet link to the territory, according to people familiar with the matter.

Google and Facebook Inc. last week asked U.S. authorities’ permission to start using the internet conduit’s branches to Taiwan and the Philippines while leaving its Chinese portion offline. The two companies helped fund the 8,000-mile Pacific Light Cable Network...