The Pentagon has signalled a delay to a decision on whether to award a lucrative cloud-computing contract to Amazon or Microsoft.
The two companies are the last ones in the running to provide artificial intelligence-based analysis and host classified military secrets among other services over a 10-year period.
The deal could be worth more than $10bn (£8.2bn).
The delay follows concerns raised by President Donald Trump last month.
He told reporters: "I'm getting tremendous complaints about the contract with the Pentagon and with Amazon."
The president added that Oracle and IBM - two companies previously knocked out of the bidding process - had been among those raising concerns.
And he said he intended to ask for the matter to be looked at "very closely" - despite the fact that the president's former spokeswoman, Sarah Sanders, had said in 2018 that he was "not involved in the process".
Last month, Republican Senator Marco Rubio also claimed the Department of Defense (DoD) had used "arbitrary criteria" to narrow down the field, which he said could "result in wasted taxpayer dollars".
Mr Rubio had previously benefited from millions of dollars-worth of campaign support from Oracle's chief Larry Ellison.
The contract was initially due to be awarded before the end of this month, and in a statement to the Politico news site. a DoD spokeswoman did not provide specifics about why the new Defense Secretary - who was appointed on 23 July - had decided to review the process.