Politicians and defence industry representatives gathered in Adelaide for a national conference yesterday were met by singing and silent protesters objecting to state and federal governments "ramping up" defence capabilities.

In his first public speech since being appointed defence minister on June 5, Senator John Faulkner told the conference the entire defence department was under review and that he intended to spend $60 billion on defence projects in the next four years.

But youth worker Keegan Brice (Brice), 25, who helped organise a prayer vigil to greet delegates as they entered the conference, said greater defence spending would only lead to reliance on the industry.

"It will get people thinking we need war for jobs, instead of thinking about things we really need such as renewable energy," he told AAP.

He didn't accept the state government's justifications for making South Australia the "defence state".

"They say projects such as the production of submarines will create jobs, but we want green jobs, not defence jobs," he said.

"Let's be the green state, not the defence state.

"If we let the SA government spend $300 million on defence, then we're basically making our economy reliant on war."

Mr Brice was one of many protesters who gathered on the steps of the South Australian Parliament and sang their hearts out in the name of peace.

Cathy Picone from the Woman's International League for Peace and Freedom said the defence and trade exhibition was part of the SA government's bid to bring more military industries to the state.

"At the moment we do need defences, but what we don't need is a defence industry which ramps up the production of armaments, which in turn causes increasing numbers of conflicts," she said.

"We need to be more and more thinking about how we can share and build trust between nations, not using the opportunities - as some are - to try to ramp up the conflict so they can sell more arms."