Vietnam is reported to have discreetly started dredging work on a disputed reef in the South China Sea in an apparent move to showcase its claims against the bigger rival, China. Satellite images show activities by Hanoi on Ladd Reef in the Spratly Islands, which is feared to trigger Beijing's anger.

The reef, which is also claimed by Taiwan, is located on the southwestern fringe of the island- where Vietnam already has a lighthouse and a small military outpost.

Satellite pictures, provided by US-based satellite firm, Planet Labs on 30 November, show newly dug channels between the lagoon and open sea as well as several vessels in a carved out embankment along the reef's edge.

Whether the vessels deployed there belong to Vietnam is not clearly visible in the images. But, it is thought that Hanoi is unlikely to let any other claimant to carry out construction work at the reef.

It could also not be ascertained why Hanoi is carrying out dredging work on the reef, but it is reported that such similar activity in the past has led to more widespread construction work on other reefs.

"We can see that, in this environment, Vietnam's strategic mistrust is total ... and they are rapidly improving their defenses," Trevor Hollingsbee, a retired naval intelligence analyst with Britain's defense ministry told Reuters. "They're doing everything they can to fix any vulnerabilities - and that outpost at Ladd Reef does look a vulnerability."

Vietnam is yet to officially comment on its activity.

Earlier in August, Vietnam had equipped several islands with mobile rocket artillery launchers that were said to be capable of striking China and its vessels across the strategic waterway.

South China Sea
Map of Spratly Islands, South China Sea, showing maritime claims of Brunei, China, Malaysia, Philippines and Vietnam Reuters

However, it is not clear how far Hanoi's activity on the reef would go this time, said Greg Poling, a South China Sea expert at Washington's Center for Strategic and International Studies. He believes it could just be an attempt by Hanoi to improve access for supply ships and fishing boats, rather than an objective to renovate the island to use it as a base.

He added that Ladd Reef could also, in theory, play a role in helping Vietnam's defend its claims in the nearby Spratly Island, where a runway is being improved and new hangars are built.

"Vietnam's knows it can't compete with China but it does want to improve its ability to keep an eye on them," Reuters quoted Poling as saying.

A spokeswoman for the US State Department, Anna Richey-Allen, said the Pentagon knew about Vietnam's reclamation work and has often raised concerns not only with Vietnam but other claimants about such activity. She said such militarisation would "risk driving a destabilising and escalatory trend. We encourage all claimants to take steps to lower tensions and peacefully resolve differences."

Vietnam has long been anxious if renewed Chinese military action would target Vietnam and drive the country off its 21 holding in the Spratly Islands.

China's territorial disputes explained IBTimes UK