Defence Minister Marise Payne has left open the possibility of bolstering Australia’s commitment to the fight against the Islamic State group.

The United States wants to “accelerate” the campaign to crush the terrorist organisation and there have been reports that could mean more foreign soldiers and military assets deployed in the Middle East.

Following her first high-level meeting with US Defence Secretary James Mattis on the sidelines of a summit in the Belgian capital, Senator Payne said that no “particular demands” had been made by America.

But she pledged to consider any new request “on its merits” and after strategists present US President Donald Trump with a new plan for speeding up the fight.

“We will see in due course – about 15 days – the final form that takes,” Senator Payne said.

Yesterday, Mr Mattis sent a stark message to America’s NATO allies, warning them to increase defence spending.

If they did not, he said, the US would “moderate” its commitment to the transatlantic alliance.

The comments were widely interpreted as a threat to several low spending European nations.

Senator Payne said Mr Mattis’s “observations were very timely” and insisted they were not relevant to Australia because the nation was on track to spend 2 per cent of GDP on defence.

“I doubt that Secretary Mattis bluffs … those who are sitting around the [NATO] table need to step up to the plate,” she said.

The Defence Minister’s discussion with her American counterpart was the first formal meeting between senior members of the Trump and Turnbull administrations.

Despite the recent fiery phone call between the Prime Minister and the President, both the US and Australia delegations declared the ANZUS alliance was in safe hands.

“I didn’t need any reassurance at all about the standing of the alliance. I am absolutely confident about the standing and the strength of the alliance,” Senator Payne said.