When China announced last week the creation of Sansha on an island in the Paracels archipelago it highlighted a key sensitivity - and potential vulnerability - for the sole rival claimant, Vietnam.
The establishment of the city, which will administer some of the territory Beijing claims in the South China Sea, also throws the spotlight on a historical contradiction in the United States' position on the regional territorial dispute, just one of several wrinkles in the decades-long saga over the Paracels.
Hanoi has been struggling amid mounting domestic pressure to push Beijing into talks over the Paracels as part of broader bilateral discussions to settle outstanding territorial disputes. The Sino-Vietnamese land border has been agreed and that in the Gulf of Tonkin settled, but Beijing has rejected overtures to include the Paracels - some of which it took by force from the South Vietnamese navy in 1974 - as part of future talks on maritime disputes.
From Beijing's perspective, as sole occupier, there is no dispute. Certainly China's state media largely ignores the Vietnamese claim, or the fact that China's occupation was completed by force.
And the creation and garrisoning of Sansha city on Woody Island - known as Yongxing Island in Chinese - suggests that is not about to change any time soon. Woody Island is already home to a military airfield and a strategic listening post.
A recent statement from the Vietnamese Foreign Ministry that confirmed Sino-Vietnamese talks to demarcate the so-called Mouth of the Gulf of Tonkin also confirmed that Hanoi is still pushing Beijing over the resource-rich Paracels, known as the Xisha Islands in Chinese and Hoang Sa Islands in Vietnamese.
'At [all] talks on sea issues so far... Vietnam has reiterated its sovereignty over the Hoang Sa archipelago,' Foreign Ministry spokesman Luong Thanh Nghi said. 'In the spirit that solution of easier issues will take priority over that of more difficult issues ... the two sides will focus on discussing the waters off the bay mouth of (Tonkin).'