An official of Huawei Technologies challenged the U.S. government this week to “substantiate” its national security concerns in the wake of the Commerce Department’s decision to block the Chinese telecom equipment maker from bidding on contracts that relate to the future nationwide broadband LTE network to be dedicated to public safety. Handed down last week, the Commerce Department ruling represents the latest setback in Huawei’s effort to establish a foothold in the U.S. market. As a result of U.S. government opposition, Huawei (the world’s second-largest provider of network equipment) abandoned its agreement to purchase U.S. equipment vendor 3Com in 2008. Earlier this year, the company was forced to divest U.S. technology firm 3Leaf Systems after the Committee on Foreign Investment in the United States (CFIUS) determined that the 3Leaf purchase—completed in 2009 without prior review or approval by CFIUS—raised significant national security concerns. Issues raised by lawmakers and other U.S. officials over Huawei’s alleged ties to the Chinese military also factored into Sprint’s decision last year to reject Huawei’s bid to participate in the carrier’s multi-billion dollar network upgrade. Asserting that national security fears cited by U.S. officials are “unsubstantiated,” William Plummer, Huawei’s Washington, D.C.-based vice president of external affairs, called on the government to “stop the manufactured fear,” declaring: “we would like to see some accountability and transparency associated with this decision.”