The US Government is considering sending military aircraft and ships to maintain freeedom of navigation around artificial islands in the disputed South China Sea.
The unidentified US official claimed that US Defense Secretary Ash Carter has placed options including sending aircraft and ships within 12nm of the reefs.
If approved by the White House, this move would directly contest Chinese territorial claims to the artificial islands.
The US considers this disputed area to be situated in international waters and airspace, and does not recognise the man-made islands as sovereign Chinese territory.
A US official was quoted by Reuters as saying: "We are considering how to demonstrate freedom of navigation in an area that is critical to world trade."
China has reportedly begun construction of its first runway on reclaimed parts of Fiery Cross Reef, which forms part of the contested Spratly Islands in the South China Sea.
The latest claims made in IHS Jane's Defence Weekly follow analysis of Airbus Defence and Space's 23 March satellite imagery, which showed a paved section of 503m x 53m runway on the north-eastern side of Fiery Cross Reef, as well as paving and ground preparation of other sections of the airstrip further along the archipelago.
In 2013, the US sent a pair of B-52 bombers over disputed islands in the East China Sea to challenge an air identification zone that China had declared in the area.