The charges relate to a criminal investigation that stemmed from a 2014 civil suit between the two companies.
It's not a vague case of Huawei's phone and software look like an iPhone or Samsung phone, either.
"The conspiracy to steal secrets from T-Mobile was a companywide effort involving many engineers and employees within the two charged companies", said Hayes.
US President Donald Trump's administration has reinstated all sanctions on Iran removed under a 2015 nuclear deal and recently imposed even stricter measures, hitting oil exports, shipping and banks.
Prosecutors also allege that Huawei stole trade secrets, including the technology behind a robotic device that T-Mobile used to test smartphones, prosecutors said.
Huawei said it had sought to discuss the charges with USA authorities "but the request was rejected without explanation".
TPG, which in 2017 paid $1.26 billion for mobile spectrum and has already spent $100 million of the $600 million construction cost, said on Tuesday it had already opted to use Huawei equipment before the government banned its inclusion in 5G networks on security concerns.
However, the criminal indictment unsealed in Seattle describes a constant stream of demands from Huawei's headquarters in China that its employees in Bellevue obtain information that T-Mobile declined to provide. U.S. security experts are concerned the equipment could be used for spying. Huawei had done business in Iran through a Hong Kong company called Skycom and alleged that Meng misled US banks into believing the two companies were separate, according to prosecutors.
Meng, who is free on bail in Vancouver after her arrest December 1 at the behest of USA authorities, is charged with bank fraud, wire fraud and two counts of conspiracy to commit both.
Her bail conditions prevent her from leaving BC and is under 24/7 surveillance, including electronic monitoring.
TPG said that it had selected Chinese firm Huawei to be its principal equipment supplier, in part because of a simple upgrade path to 5G. "The Department of Homeland Security is focused on preventing nefarious actors from accessing or manipulating our financial system, and we will ensure that legitimate economic activity is not exploited by our adversaries".
The allegations by the US Department of Justice are the most serious Huawei has ever seen, and go to the heart of the trade war between China and the US.
"These are very serious actions by a company that appears to be using corporate espionage not only to enhance their bottom line but to compete in the world economy", Whitaker said. Last year, Chinese peer ZTE Corp was prevented from buying essential components from US firms after pleading guilty to similar charges, crippling its operations.
The charges were announced just before a crucial two-day round of trade talks between the United States and China are scheduled to begin in Washington.
TPG states it continued to roll-out Huawei equipment prior to the government's announcement, however, concludes there's no commercial sense to pursue.
The indictments came amid tense trade negotiations between the United States and China. China has retaliated with tariffs of its own.