SYDNEY, Nov 26 (Reuters) - Australia's Indian Ocean

territory of Christmas Island will be connected by subsea cable

to the northern garrison city of Darwin, a project backed by

Alphabet's Google that Australia says will boost its

digital resilience.

Christmas Island is 1,500 km (930 miles) west of the

Australian mainland, with a small population of 1,250, but

strategically located in the Indian Ocean, 350 km (215 miles)

from Jakarta.

The cable announcement comes as the Australian and U.S.

militaries upgrade airfields in Australia's north, where a

rotating force of U.S. Marines will be joined by Japanese troops

next year.

Google's vice president of global network infrastructure,

Brian Quigley, said in a statement the Bosun cable will link

Darwin to Christmas Island, while another subsea cable will

connect Melbourne on Australia's east coast to the west coast

city of Perth, then on to Christmas Island and Singapore.

Australia is seeking to reduce its exposure to digital

disruption by building more subsea cable pathways to Asia to its

west, and through the South Pacific to the United States.

"These new cable systems will not only expand and strengthen

the resilience of Australia's own digital connectivity through

new and diversified routes, but will also complement the

Government's active work with industry and government partners

to support secure, resilient and reliable connectivity across

the Pacific," said Communications Minister Michelle Rowland in a

statement.

The other partners in the cable project include Australian

data centre company NextDC ( NXDCF ), Macquarie-backed

telecommunications group Vocus, and Subco.

Subco previously built an Indian Ocean cable from Perth to

Oman with spurs to the U.S. military base of Diego Garcia, and

Cocos Islands, where Australia is upgrading a runway for defence

surveillance aircraft.

Although 900 km (560 miles) apart, Christmas Island is seen

as an Indian Ocean neighbour of Cocos Islands, which the

Australian Defence Force has said is key to its maritime

surveillance operations in a region where China is increasing

submarine activity.

The new cables will also link to a Pacific Islands network

being built by Google and jointly funded by the United States,

connecting the U.S. and Australia through hubs in Fiji and

French Polynesia.

Vocus said in a statement the two networks will form the

world's largest submarine cable system spanning 42,500 km of

fibre optic cable running between the U.S. and Asia via

Australia.

(Reporting by Kirsty Needham in Sydney; Editing by Lincoln

Feast.)