Speaking in Sydney on Tuesday morning, Charges d'affaires Jim Carouso said the murder of at least 59 people - the US's worst mass shooting - would kickstart another round of debate about US firearm control but pointedly drew a contrast with Australia's success in stopping gun violence.

"When Prime Minister Howard after the Port Arthur massacre made the political decision that this must not stand, he took incredible flak. He had to wear body armour is my understanding, for months after that. But he carried it through," Mr Carouso said.

He said the US was "still having that debate", including about the meaning of the Second Amendment, which protects the right to keep and bear arms but dates back to 1791 and is premised on the fact that a "well-regulated militia" is needed to secure a free state.

Mr Carouso said he didn't know how that debate would turn out.

"It's a very, very difficult problem that we've been wrestling with for years and years ??? Every time one of these things happens, US analysts always point to what happened in Australia and point out that your murder rate with guns has gone down drastically. You haven't had a repeat of this sort of mass murder other than the Lindt Cafe event.

"So I think certainly a lot of observers in the US look to the Australian example."

Mr Carouso described the Las Vegas shooting as "horrific".

"This is a single individual who is able to create such incredible carnage. What can you say? It's awful."

He thanked Prime Minister Malcolm Turnbull for extending his condolences and thoughts on Tuesday morning at a breakfast to open the Sea Power naval conference in Sydney.

Mr Howard led a dramatic tightening of gun laws across the nation in the wake of the 1996 Port Arthur massacre in which 35 people were killed. Amid a political backlash, he was famously photographed during his campaign for gun law reform with the outline of body armour clearly visible on his jacket.

Mr Turnbull said the Las Vegas shooting was a reminder there was no place for "set and forget" in Australia's national security.

"This is a reminder that we must constantly work to stay ahead of the threat, whatever the motives of threat, whatever the motives of those who seek to do us harm," he said, praising Mr Howard's gun control laws.

"And we remain ever vigilant to maintain them," he said.