KO OLINA, Hawaii (Reuters) - The threat that violent extremist groups pose to Southeast Asia is growing each year as they become more organized and focused in their aims, Singapore Defense Minister Ng Eng Hen said on Friday.

Singapore's Defence Minister Ng Eng Hen waits to speak at a plenary session of the 11th International Institute of Strategic Studies (IISS) Asia Security Summit: The Shangri-La Dialogue in Singapore June 3, 2012. REUTERS/Tim Chong

Ng was speaking to reporters following a meeting of Southeast Asia defense ministers with U.S. Defense Secretary Ash Carter in Hawaii, where the defense chiefs devoted a major chunk of time to discussing the threat from Islamic State and similar groups.

Over 1,000 Southeast Asians have flocked to join Islamic State’s self-declared “caliphate” in Iraq and Syria, Ng said.

“Every year we meet, the situation and threat from extremist terrorism rises,” Ng said. “Compared to, say, a year or even two years ago, they’re more organized...they’re more networked, they’re more clear in their articulation of what they want to achieve.”

Security officials said in June that Southeast Asian militants who claim to be fighting for Islamic State said they had chosen one of the most wanted men in the Philippines to head a regional faction of the group.

Authorities in the region have been on heightened alert since Islamic State claimed an attack in the Indonesian capital Jakarta in January in which eight people were killed, including four of the attackers.

Ng cited a recent plot in which an Indonesian cell coordinated by an Islamic State member in Syria had planned to shoot up hotels in Singapore’s Marina Bay area. The plot was foiled by Indonesian authorities, he said.

“They have gone beyond networks to push the flow of funds, weapons. They are already plotting,” Ng said.

U.S. defense officials believe that hundreds of citizens from Southeast Asia have returned to their home countries after joining Islamic State in Iraq and Syria, raising concerns that they may try to launch a wave of attacks.

Ng said Southeast Asian defense chiefs believe that if Islamic State were destroyed in its base in Iraq and Syria, that would actually increase the risk to their region in the short-term, because seasoned Islamic State fighters would likely return home. The United States is leading an air campaign to dislodge Islamic State from Iraq and Syria.

“They would decide to come back, some re-energized, some trained and the networks would still be existing,” Ng said.