Officials provided few details about the trip.
New South Wales police said the couple's trip did not trigger any security alerts, although Australian counter-terrorism officials confirmed they investigated the son's activities for six months in 2019 for potential extremist associations.
Officials in the Philippines say there is no evidence the couple received military training during the November trip and strongly reject suggestions their country is a hotbed of terrorism.
“A mere visit does not support allegations of terrorist training, and the length of their stay would not allow for any meaningful or structured training,” National Security Adviser Eduardo Año. said on Wednesday.
Pockets of extremism persist, experts say
While terrorism in the predominantly Catholic country has dropped significantly, especially since then-President Rodrigo Duterte passed a sweeping anti-terrorism law in 2020, dozens of militants who support ISIS ideology remain fragmented in Mindanao, experts say.
“Just because the insurgency has ended doesn't mean those hundreds of Islamic State true believers are gone,” said Greg Barton, chair of global Islamic politics at Deakin University in Australia.
Mindanao was colonized by Spanish, American and Filipino Christian settlers, reducing the Muslim majority population to a minority. In recent decades, the resource-rich region has been plagued by violence that has killed an estimated 150,000 people and bloody battles for land and political power.
Mindanao also became a stronghold for radical Islamist groups that pledged allegiance to al-Qaeda in the late 1980s and '90s. When al-Qaeda was suppressed, many remaining fighters defected to ISIS.
