Amazon has filed an intention to appeal the US Department of Defense’s decision to give a major contract to Microsoft.
Amazon had been considered the favourite to win the deal, worth $10bn over the next 10 years.
The company, which already provides cloud computing to the US Central Intelligence Agency, said the decision was made due to political pressure.
In July, President Donald Trump threatened to intervene after what he described as “tremendous complaints”.
Mr Trump had previously attacked Amazon chief executive Jeff Bezos, who also owns the Washington Post.
The Pentagon subsequently delayed its decision to award the contract until 25 October, when it was announced the work would be given to Microsoft. The Joint Enterprise Defense Infrastructure project – known as JEDI – is designed to modernise the antiquated data sharing systems within the US military.
An Amazon spokesperson told the BBC: “Amazon Web Services is uniquely experienced and qualified to provide the critical technology the US military needs, and remains committed to supporting the DoD’s modernisation efforts.
“We also believe it’s critical for our country that the government and its elected leaders administer procurements objectively and in a manner that is free from political influence.
“Numerous aspects of the JEDI evaluation process contained clear deficiencies, errors and unmistakable bias – and it’s important that these matters be examined and rectified.”
The BBC understands Amazon submitted its intention to protest the decision to the Court of Federal Claims last Friday.
A Department of Defense official told the BBC it would not speculate on potential litigation.