Amazon’s likely claim to the Pentagon’s $10 billion cloud computing deal, dubbed JEDI, was thrown into question Thursday after the Department of Defense (DoD) put the hotly contested contract on hold, pending review by recently appointed Secretary of Defense Mark Esper.

Elissa Smith, a Pentagon spokeswoman, told reporters that “Secretary Esper is committed to ensuring our warfighters have the best capabilities, including artificial intelligence, to remain the most lethal force in the world, while safeguarding taxpayer dollars,” according to the New York Times and other media outlets.

The Joint Enterprise Defense Infrastructure contract — a 10-year deal with the DoD to provide cloud services for all branches of the military — has been a source of ongoing controversy.

The contract, which initially, drew bids from cloud giants, Amazon, Microsoft, Oracle, IBM, and Google, has narrowed significantly since JEDI was announced last fall.

Google was the first to pull its bid in October citing conflicts with JEDI’s use of AI. In April, the DoD disqualified bids from IBM and Oracle bids because they did not meet the “minimum requirements” for working with highly classified and sensitive military data. That leaves just Microsoft Azure and Amazon Web Services (AWS) in the running.

However, AWS — which already provides cloud services for the C.I.A. — is considered by many to be the frontrunner. And despite being eliminated, Oracle continues to challenge the requirements for the contract.

Whether Esper could spell trouble for Amazon’s prospects remains to be seen. But his involvement in JEDI’s ongoing saga comes as little surprise given President Donald Trump’s apparent grudge against Amazon founder Jeff Bezos.

Nextgov reports that in late July, Esper said the JEDI contract was “one of the things I want to take a hard look at.”

Thursday’s announcement is the latest hurdle in a string of protests, legal challenges, and claims of favoritism that has punctuated the lucrative military contract.