The state government has pledged whatever it takes to fix the granite and bronze plaque which took pride of place at the Vietnam War Memorial Cherry Tree Walk.

Furious Vietnam vets condemned the desecration of the plaque, which carried the names of 18 soldiers who lost their lives in the war.

Bob Carr and others have joined the chorus of outrage, with NSW parliamentary secretary and MP for Campbelltown, Graham West branding the offenders as 'idiots'.

"You have to wonder what goes through the heads of these idiots," Mr West said.

"The men and women who were involved in Australia's military efforts in Vietnam served their country with pride, living up to the highest ANZAC traditions.

"Keeping the memory of these veterans safe is the least we can do.

"Their commitment and sacrifice deserves to be treated with the utmost respect- not by an act of vandalism by a bunch of cowardly louts."

The attack marked the sixth time the area had been damaged since its 1996 opening.

"As well as public shame, I want to see the book thrown at them."

The cost of repairing the damage is believed to amount to several thousand dollars.

"I think it's outstanding that the government are helping out and it came as a real surprise," Vietnam vet Tony Blake said.

"It will really take the burden and worry out of it for all the vets in the Highlands."

The work should be done in time for the visit by Governor-General Michael Jeffery in February.

The damaged plaque bore the name of dead soldiers from the governor-general's own battalion.