A Howard government defence minister says the US made a mistake in how it handled Iraq, as Australia considers whether to join another American strike.

Australia’s defence minister during the US-led invasion of Iraq in 2003 has criticised what the Americans did after Saddam Hussein was toppled.

Robert Hill says the outlawing of the Iraqi Republican Guard and Hussein’s Ba’ath Party were mistakes in the attempt to turn the country from a dictatorship.

He said dismantling those institutions took away from the people a “feeling of perspective of where they stand in relation to those that rule and those that protect them”.

“A democracy without that institutional foundation simply wasn’t going to work,” he told Griffith University’s Global Integrity Summit in Brisbane on Wednesday.

“When you’re trying to facilitate the introduction of a new system of governance, it’s very difficult to do it in a vacuum.”

The former Liberal senator’s critique comes as Australia considers how it would respond to any possible request from Washington for help in ousting the jihadist Islamic State group, which has a foothold in northern Iraq and Syria.

But Mr Hill, who is now an adjunct professor at the University of Sydney’s United States Studies Centre, declined to comment on whether Australia should join a US-led operation in Iraq or if the toppling of Hussein created a power vacuum for extremist groups to exploit.

“I’ve got strong views on the subject and I am not getting into politics,” he told AAP.

“I’m out of politics. I’m not a politician.”