Lt. Gen. Eugenio Cedu said groups likely to attempt a disruption are trapped in Sulu, the Manila Times reported.
The heads of the 16 states belonging to the Association of Southeast Asian Nations are scheduled to attend the meeting from Jan. 11 to Jan. 15. The summit was postponed from December because of a threatening typhoon.
Four countries -- Canada, Australia, Britain and New Zealand -- have advised their nationals to stay away from southern and central areas during the summit. Canada's advisory said the country had received credible information of a threat.
The Philippines has no plans to postpone the event.
"With a deep sense of pride and national unity, let us put our best foot forward as the Philippines hosts these historic meetings," President Gloria Arroyo told military officials at Camp Aguinaldo.
Police: Sword-wielding man demanded free tacos
Puzzle-maker slips 'Murdoch Is Evil' into Rupert Murdoch's Sunday Telegraph