The Philippines, Malaysia and Indonesia will begin joint patrols and information-sharing to curb the influence of local Islamist terror groups, according to a joint statement released by the three governments.
The Trilateral Maritime Patrol Indomalphi -- whose name incorporates elements of each of the three countries' names -- was "initiated and implemented" by the governments of the "three in order to face the security challenges associated with each country's border waters," according to the statement.
The start of the initiative was marked with a ceremony aboard an Indonesian naval vessel in the Javanese province of North Kalimantan Monday, attended by the defense ministers of the three countries, alongside each nation's armed forces commander.
"The Trilateral Maritime Patrol Indomalphi is a concrete step taken by the three countries ... in maintaining stability in the region in the face of non-traditional real threats such as piracy, kidnapping, terrorism and other transnational crimes in regional waters," the statement said.
To implement the increased intelligence sharing and joint patrols, there will be a Maritime Command Center (MCC) in each nation -- Tarakan in Indonesia, Tawau in Malaysia and Bongao in the Philippines. The maritime patrols will also include air and land elements.
Chief among the issues that the Southeast Asian nations face is the rising threat of local terror groups from the three countries, who use the channels and inlets of the nations' coastlines on the Sulu Sea to move weapons, cash and personnel between the Indonesian island of Java, Malaysia's Sabah province and the Philippines' Mindanao, a large southern island with a large Muslim population and a long history of religiously-motivated separatism.
Kidnappings, especially by Mindanao-based militants of Indonesian nationals, has also been a key issue in moving the initiative forward.
In addition to dozens of Indonesians, mainly fishermen and seamen, kidnapped in the past few years, the Sulu-based faction of the Abu Sayyaf Group (ASG) recently kidnapped two Canadians, a Norwegian and a Philippines national from a marina in the southern Philippines.
Most recently an alliance of ISIS-aligned groups in Mindanao have organized to sweep into the Mindanao city of Marawi, holding territory in the city of some 200,000 people for a month. It is the first instance of disparate, ISIS-aligned Filipino groups banding together and holding territory
Philippines Armed Forces (AFP) operations continue but have not been able to yet dislodge a core group of militants, organized by the infamous Maute group and led, ultimately, by the ASG leader Isnilon Hapilon, who has been declared the emir of Southeast Asia by ISIS' leader, Abu Bakir al-Baghdadi
"This is a warning so we can be ready to address this together because there are sleeper cells that are in each of our countries," Indonesian military chief Gen. Gatot Murmatyo said at the ceremony.
"With this trilateral cooperation it will ease the exchange of information because the speed and accuracy of information is very much needed to put in place measures and anticipate the possible escape of (militants) out of Marawi."
Despite the three nations' increasing issues with ISIS-inspired terrorism and their long unguarded coastlines bordering the Sulu Sea, long used for smuggling routes, active cooperation between the countries' governments has been lacking, Sidney Jones, director of the Institute for Policy and Analysis of Conflict told CNN last week.
"Part of the problem is that borders in this archipelago are extremely porous. It's still possible to get in by boat. All three countries -- Malaysia, Indonesia and the Philippines -- are trying to strengthen their border controls and their immigration checks," the Jakarta-based regional terrorism expert said.
"One thing that's needed is a common watch list so that all three countries are operating from the same information about who may be dangerous. But regional cooperation is improving on that."