Tech titans including Amazon and Microsoft have already spent months jockeying for a winning offer on the prestigious contract, which could be worth as much as $10 billion over a decade.

The Joint Enterprise Defense Infrastructure, better known by its nerdy name JEDI Cloud Program, ultimately will see all military branches sharing information in one system that can be scoured in real time with the help of artificial intelligence.

Currently, the Navy, Air Force and Army use separate clouds, so the benefits of immediately shared information, for instance by a pilot, could be huge.

He or she might have instant access to data collected by troops on the ground, a drone or a ship at sea, speeding the flow of vital intelligence.

Pentagon Chief Information Officer Dana Deasy said the Defense Department is appealing to outside firms because it needs help learning how to put in place a cloud of this scope.

"Battlefield advantage is driven by who has access to the best information that can then be analyzed to inform decision-making at the point of time and need," Deasy said.

While JEDI will play a key role for future cloud needs, officials noted the Pentagon will continue to operate multiple cloud systems, for now at least.

Tech firms including Microsoft and Amazon have in recent weeks festooned the metro stop underneath the Pentagon with advertisements boasting of their cloud prowess, no doubt hoping to catch the eye of decision-makers in the building.

The contract will have an initial duration of two years, but can be renewed for various amounts of time up to 10 years.

And of course the bid winner will have a foot in the Pentagon door, potentially leading to other lucrative defense contracts.

A Silicon Valley backlash in recent months has seen thousands of tech workers protest their companies getting involved with the Pentagon.

In May, Google workers signed a petition protesting the firm's involvement with the military in developing artificial intelligence to make US military drones better at recognizing what they are monitoring.

Google last month said it would not use AI for weapons or to "cause or directly facilitate injury to people," as it unveiled a set of principles for the technologies.