Jakarta. The Indonesian Air Force deployed three Sukhoi fighter jets to the Tarakan air base in North Kalimantan, as part of efforts to prevent Islamic State-aligned Maute militants from crossing into the country from the Southern Philippines.

Maute group militants are currently fighting Philippine government forces in Marawi City on the southern island of Mindanao – a battle that has been waging now for over three weeks. 

Mindanao, the largest of Philippine's most southern islands, can be reached by boat from North Maluku's Morotai Island in just over five hours.

Tarakan base commander Col. Didik Krisyanto said the three Sukhoi jets arrived on Friday (16/06) and are expected to stay for a month.

"The militants might flee the Philippines and cross the border into Indonesia," Didik said.

The Indonesian Navy has also been closely watching the Indonesia-Philippine sea border from its outpost, according to Col. Setiyo Widodo, currently the commander at the Tahuna-Sangihe naval base in north Sulawesi.

Although the navy conducts daily sea patrols, the escalating security situation in the Philippines demands more comprehensive measures, Setiyo said.

"The navy has been in coordination with the army and police in Sangihe to guarantee the district’s security [...] We’ve informed the people to report any suspicious activities or persons to the authorities in the area," Setiyo said.

The colonel added that fishermen, who make up most of the population in the district, are reliable informants on any suspicious movements in the sea and coastal areas.