A deal signed in South Korea by Huawei Technologies, the Chinese telecommunications giant, could undermine Washington's defense ties with Seoul, according to two powerful U.S. senators.
Dianne Feinstein and Robert Menendez, respectively the chairs of the Senate's intelligence and foreign affairs committees, said in a letter that "maintaining the integrity of telecommunications infrastructure" was critical to the alliance.
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Congress has long objected to Huawei expanding its business in the U.S. but the letter is a rare example of political leaders in the country making an issue of the Chinese company's investments offshore.
U.S. suspicions about Huawei could also rebound on American technology companies abroad in the wake of documents leaked by former intelligence contractor Edward Snowden outlining their co-operation with Washington's spy agencies.