Plans for the data centre on the tiny island located 350 km (220 miles) south of Indonesia have not previously been reported, and many details including its projected size, cost and potential uses, remain secret.

However, military experts say such a facility would be a valuable asset on the island, which is increasingly seen by defence officials as a critical frontline in monitoring Chinese submarine and other naval activity in the Indian Ocean. 

Google is in advanced talks to lease land near the island's airport to construct the data hub, including a deal with a local mining company to secure its energy needs, Christmas Island Shire officials told Reuters and council meeting records show.

Alphabet Inc-owned Google GOOGL.O declined to comment for this story. 

Australia's Department of Defence had no comment.

A recent tabletop war game involving the Australian, US and Japanese militaries highlighted Christmas Island's role as a forward line of defence for Australia in any regional conflict, particularly its advantages for launching unscrewed weapons systems.

Bryan Clark, a former US Navy strategist who ran the war games, said having a forward "command and control" node on Christmas Island would be critical in a crisis with China or another adversary.

"The data centre is partly to allow you to do the kinds of AI-enabled command and control that you need to do in the future, especially if you rely on uncrewed systems for surveillance missions and targeting missions and even engagements," Clark, now a Hudson Institute fellow, told Reuters. 

Subsea cables provide more bandwidth for communication than a satellite, and greater reliability, because China would be expected to jam satellite communications or Starlink in a crisis, he said. 

"If you've got a data centre on Christmas, you can do a lot of that through cloud infrastructure," he added. 

Australia's defence department entered into a three-year cloud agreement with Google in July. Britain's military recently announced a similar Google cloud deal, which it said will boost intelligence sharing with the United States. 

Google applied last month for Australian environmental approvals to build the first subsea cable connecting Christmas Island to the northern Australian city of Darwin, where the US Marine Corps are based for six months of the year.

The cable link to Darwin for Google will be installed by US company SubCom, documents show. Reuters has reported SubCom, the exclusive undersea cable contractor to the US military, previously connected the US/UK military base of Diego Garcia in the Indian Ocean to a cable stretching from Australia to Oman.

Christmas Island Shire President Steve Pereira said his administration is examining the community impact of the proposed data centre before giving final construction approval.

The 135 square km (52 square mile) island, best known for its asylum seeker detention centre and annual migration of millions of red crabs, has until recently struggled with poor telecommunications and its 1,600 residents lack job opportunities. 

"There is support for it, providing this data centre actually does put back into the community with infrastructure, employment and adding economic value to the island," he said.

Two Christmas Island sources and a defence source said the data centre was of commercial benefit to Google because of the Indian Ocean location between Africa, Asia and Australia, as well as its potential defence uses.

Another recent war game on Christmas Island involved the rapid deployment of an advanced US HIMARS truck-mounted rocket system from Darwin, which drew a mixed response from residents.

Some anti-war protesters were fearful of the impact on tourism, while business people are hopeful increased defence activity will boost the economy, Pereira said. 

"We are a strategic asset for defence," he said.

"There are many industries on the island we have to protect, all of this will be closely considered for any new projects - whether it be defence or Google," he added.

Retired Navy Commodore Peter Leavy, who lived on the island as a student, told Reuters he has taken several Australian defence groups to Christmas Island since last year, seeking to build community support for defence activities.

"Christmas Island is quite well positioned to at least monitor what is going through Sunda Strait, Lombok Strait, Malacca Straits. It is a really good location."