U.S. officials granted Google permission to turn on a high-speed internet link to Taiwan but not to the Chinese territory of Hong Kong, citing national-security concerns in a ruling that underscores fraying ties between Washington and Beijing.

“There is a significant risk that the grant of a direct cable connection between the United States and Hong Kong would seriously jeopardize the national-security and law-enforcement interests of the United States,” the U.S. Department of Justice said in its Wednesday decision, which was backed by the departments of Homeland Security and Defense.

The agencies instead urged the Federal Communications Commission to grant Google owner Alphabet Inc. permission to start using the portion of its 8,000-mile underwater Pacific Light cable that connects California to Taiwan. The commission approved that request Wednesday afternoon.

Crews have already built the multimillion-dollar cable with branches to Taiwan and Hong Kong, but it remains dormant. The FCC has final authority over licenses to operate submarine cables, though it usually defers to other agencies on projects’ national-security reviews.

The decision threatens to end Hong Kong’s dominance as a top destination for U.S. internet cables and puts at risk several ongoing projects, including a Facebook Inc. -backed fiber-optic line linking Los Angeles to Hong Kong and a Google-backed project linking Hong Kong to the U.S. territory of Guam.