The announcement comes after larger rival China Telecom had its licence to operate in the US revoked in October. FCC chairwoman Jessica Rosenworcel said: "There has been mounting evidence - and with it, a growing concern - that Chinese state-owned carriers pose a real threat to the security of our telecommunications networks."
China Unicom told the BBC its American unit "has a good record of complying with relevant US laws and regulations and providing telecommunication services and solutions as a reliable partner of its customers in the past two decades". "China Unicom (Hong Kong) Limited will closely follow the development of the situation," it added.
