Five Republican senators sent a letter to Microsoft on Tuesday stressing that Chinese telecommunications giant Huawei poses a “real and urgent” threat after an executive at the American tech giant complained the U.S. hasn't been open about why Huawei was blacklisted.

The letter from GOP Sens. Tom Cotton Tom Bryant CottonThe Hill's 12:30 Report: Trump stokes fears over November election outcome The Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Abortion stirs GOP tensions in Supreme Court fight MORE (Ark.), Marco Rubio Marco Antonio RubioGOP lawmakers distance themselves from Trump comments on transfer of power McConnell pushes back on Trump: 'There will be an orderly transition' Graham vows GOP will accept election results after Trump comments MORE (Fla.), Rick Scott (Fla.), Josh Hawley Joshua (Josh) David HawleyHillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Trump faces tricky choice on Supreme Court pick FBI director warns that Chinese hackers are still targeting US COVID-19 research MORE (Mo.) and Mike Braun Michael BraunTrump plans to pick Amy Coney Barrett to replace Ginsburg on court Trump dumbfounds GOP with latest unforced error Pessimism grows as hopes fade for coronavirus deal MORE (Ind.) to Microsoft President and Chief Legal Officer Brad Smith details several allegations of “espionage activities” and “technology theft and economic warfare."

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in May directed the Commerce Department to place Huawei on its "Entity List." U.S. companies are forbidden from doing business with firms on the list, but the government has granted Huawei multiple "general temporary licenses" since.

The U.S. has long considered Huawei a national security threat because of its deep connections to the Chinese government.

Smith last month in an interview with Bloomberg Businessweek said that Microsoft has asked U.S. regulators to explain the decision to blacklist Huawei multiple times.

“Oftentimes, what we get in response is, ‘Well, if you knew what we knew, you would agree with us,’” Smith said. “And our answer is, ‘Great, show us what you know so we can decide for ourselves. That’s the way this country works.’”

In their letter Monday, the senators said that publicly available information is enough to prove Huawei should be reprimanded.

“We also understand that many American companies have conducted business in good faith with Huawei and other Chinese telecommunications companies," they wrote.

"While the U.S. government and American industry must take certain steps to protect our people and our telecommunications infrastructure, we do not want to cause undue harm to those American companies. We believe, however, that a review of publicly available evidence indicates that the security concerns about Huawei are real and urgent.”