It has been eight years since the Philippines declared victory over the Islamic State, or ISIS. But the threat from ISIS has become smaller and fragmented, with lethal attacks by militants linked to the group rocking the country intermittently.

On Tuesday, that threat came under fresh scrutiny.

The suspects in the Bondi Beach massacre in Sydney, Australia, were motivated by ISIS and had traveled to the Philippines, Australian officials said. The Philippine authorities then said that the two men had traveled to the city of Davao last month. It remains unclear what they were doing there.

Sajid Akram, an Indian national, and Naveed Akram, an Australian citizen, arrived in the Philippines together on Nov. 1 from Sydney, said Dana Sandoval, a spokeswoman for the Philippine Bureau of Immigration. The men left the country on Nov. 28, flying to Sydney via Manila, Ms. Sandoval added.

Davao is the largest city on the southern island of Mindanao, where Muslim insurgents have long sought to carve out an independent state. In 2017, ISIS fighters held siege to the city of Marawi in Mindanao for five months, prompting the Philippine government to unleash an all-out war, killing key leaders and forcing combatants to surrender.

Hundreds of Islamic State fighters remain in the Philippines, a Catholic-majority country, according to experts. The groups continue to recruit, leveraging local poverty and historical political grievances in Mindanao.

The terror groups have shifted gears — they have become smaller and factionalized, but still hold an allegiance to the Islamic State.

And they have continued to target police forces and Christian places of worship. In 2023, Islamic militants detonated an explosive device during a Catholic Mass at Mindanao State University in Marawi, killing four people and injuring dozens.

Rommel Banlaoi, an antiterrorism expert in the Philippines, said there was a shift in militancy movements in the region after the Marawi siege.

“Before, the focus was on creating an Islamic state. Now it has transformed to helping Muslims, Palestinians displaced by the Middle East violence,” Mr. Banlaoi said.

In recent years, the government has sought to offer some of these fighters opportunities for peaceful reintegration. Many of these militants have surrendered because of exhaustion and disillusionment with the failed attempt to establish an Islamic caliphate.

The Philippines also established the Bangsamoro Autonomous Region in Muslim Mindanao to give residents a sense of greater political autonomy and to strip extremist groups of their support base, even though the first local election was repeatedly delayed because of the fragile peace process.

Sui-Lee Wee is the Southeast Asia bureau chief for The Times, overseeing coverage of 11 countries in the region.