Story highlights China is building islands in disputed waters in the South China Sea

Land reclamation taking place at five sites, IHS Jane's Defence Weekly says.

China creating 'chain of air and sea capable fortresses'

Hong Kong (CNN) China is building a "significant presence" in disputed waters in the South China Sea through land reclamation, new analysis shows.

Satellite images from late January analyzed by IHS Jane's Defence Weekly show that China is reclaiming a significant amount of land at three sites in the Spratly Islands, in addition to two other sites previously documented by the defense publication.

"Where it used to have a few, small concrete platforms, it now has full islands with helipads, airstrips, harbors, and facilities to support large numbers of troops," James Hardy, Jane's Asia Pacific editor, told CNN.

"We can see that this is a methodical, well-planned campaign to create a chain of air and sea capable fortresses across the center of the Spratly Islands chain."

In November, the publication reported that China was building an "air strip capable" island at least 3,000 meters long on Fiery Cross Reef.

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