Facing an emboldened and heavily armed China in a territorial stand-off, Vietnam is looking to swell its naval reputation with enhanced firepower and renewed pride in its maritime past.

Vietnam, hardly known for its naval prowess despite 3,200 kilometres (2,000 miles) of coastline, is keen to show its commitment to two strategically important and reputedly resource-rich island chains in the South China Sea also claimed by Beijing.

Hanoi has accelerated spending on sea power in recent years to counter the increasing dominance of the Chinese navy, experts say, and reassure a Vietnamese population wary of its larger neighbour and former coloniser.

A hitherto little-known sea route used by the Communist north in the war against US-backed South Vietnam has provided just the right propaganda to show that when it comes to fighting Hanoi, bigger does not necessarily mean better.

At a recent event to mark the 50th anniversary of the Ho Chi Minh Sea Trail -- a supply route that delivered soldiers, medicines and arms to the Viet Cong -- much was made of the tales of out-gunned sailors outwitting a mighty enemy.

"History is being used for current disputes. It is a demonstration that Vietnam has a maritime tradition," said Vietnam expert Professor Carl Thayer of the University of New South Wales in Australia.

He said the focus on the anniversary "plays into nationalism and it makes the government more legitimate because its the modern-day inheritor of that legacy."

A ceremony in the coastal city of Haiphong, around two hours' drive north of Hanoi, was attended by Vietnamese President Truong Tan Sang, broadcast live on television and given prominent coverage in state-run newspapers.

"Between 1961 and 1975, these small ships won over America's modern weapons," said Sang, adding that "thousands of weapons and tens of thousands of soldiers" were transported by the sea route.

Veteran Nguyen Quang Mui, looking like he still spends much of his time in his naval uniform, proudly told reporters about his time on the "no-number fleet", so-called because their boats were stripped of identifying markers.

"We were ordered to protect our force and secretly bring our goods onshore at any price... We did not think of death," the 70-year-old told AFP at the anniversary event last month.

Mui described his "most dangerous" trip when, tasked with delivering weapons to Vietnam's southern coast under the cover of darkness, the ship found itself surrounded by three US vessels.

Despite an enemy "one hundred times more modern", the mission was a success.

That former foe has become an ally in the context of the present-day spat as China's claim to essentially all of the South China Sea, a key global trading route, has prompted the US to pledge a continued presence in the region.

Vietnam's annual naval procurement budget has jumped by 150 percent since 2008 to $276 million this year and is expected to hit almost $400 million by 2015, according to defence and security intelligence group IHS Jane's.

But in August, the Pentagon estimated China's overall military-related spending was more than $160 billion in 2010 and said Beijing was increasingly focused on naval power, with investment in new hi-tech weaponry.

That same month Vietnam received the second of two Russian-made frigates ordered several years ago as part of a naval upgrade that also includes maritime patrol aircraft and six submarines.

"Until the recent procurement drive from Russia, the navy was in a poor state, with largely obsolete equipment," IHS analyst Alex Pape said.

Most of Vietnam's recent purchases are smaller missile-armed warships that would be a deterrent against the better-equipped Chinese navy but "would not be survivable in a direct, sustained war-fighting scenario," he added.

While conflict is still just a threat, an editorial in China's Global Times newspaper, closely linked to the ruling Communist Party, last month warned countries with rival territorial claims to "prepare for the sounds of cannons".

The neighbours are at loggerheads over the Spratly archipelago -- also claimed by the Philippines, Taiwan, Brunei and Malaysia -- as well as the Paracel islands, annexed by China in 1974 and believed to be used for intelligence gathering.

In May, Vietnam accused Chinese marine surveillance vessels of cutting exploration cables of an oil survey ship inside its exclusive economic zone.

Footage on YouTube apparently showing an unidentified Vietnamese ship ramming a Chinese surveillance boat has also emerged recently, although it has not been verified by either side.

Last month China and Vietnam pledged to settle their disputes through "friendly consultations".

But the maritime issue has sparked an unprecedented string of small-scale nationalist protests in major Vietnamese cities in recent months, at first tolerated by the authorities, but later broken up with demonstrators arrested.

At the anniversary event, models of vessels recently purchased from Russia were prominently displayed, along with romanticised posters depicting a steely-eyed sailor with a bayonet poised to defend the Spratlys.

A local official, pointing at a poster, told AFP that China wanted to take Vietnam's islands -- "It is not fair!" he exclaimed.