The US and Australia yesterday warned of the growing threat to South-east Asia from foreign fighters returning from the Middle East, saying a new "annihilation" tactic in Iraq and Syria was specifically aimed at preventing foreigners from escaping.

After a summit in Sydney, ministers from both countries released a joint statement that stressed the need to work with regional partners to address "the threat of returning foreign fighters, cyber threats, and maritime security".

The statement, which cited recent terrorist attacks in Britain, the Philippines and Indonesia, followed a meeting between Defence Secretary James Mattis and Secretary of State Rex Tillerson from the United States and their respective counterparts from Australia, Ms Marise Payne and Ms Julie Bishop.

Mr Mattis said his country's "annihilation" tactic - first announced last month - was designed to prevent foreign fighters in the Middle East from returning to their homes.

"In this campaign, where before we were shoving them from one town to another and they're falling back, we now take the time to invest the town and make certain that foreign fighters cannot escape to return to Paris, France, to Australia, to wherever they came from, and bring their message of hatred and their skills back to those places and attack innocent people," he said.

Ms Payne said Australia strongly supported the tactic and was keen to address the Islamic State in Iraq and Syria's (ISIS) links across the region.

Her comments follow concerns that non-Asian fighters have been supporting an insurgency by militants in the city of Marawi in the southern Philippines.

"For Australia, from our perspective today, it's important that we do discuss ISIS' links in South-east Asia, violent extremist organisations and the risk that returning foreign fighters who may endeavour to resume positions in their own countries might pose in this region," Ms Payne said ahead of the meeting.

"They'll come back with battlefield skills, they'll come back with hardened ideology, they'll come back angry, frustrated, and we need to be very aware of that."

Mr Mattis said Australia and the US were "united (in) our resolve, even against an enemy that thinks by hurting us they can scare us".

"Well, we don't scare," he added.

During the summit, Mr Tillerson also highlighted the threat from North Korea's nuclear weapons programme and singled out China for failing to pressure Pyongyang as well as militarising islands in the South China Sea.