The violence serves as a reminder that, despite a historic accord with the Philippines' largest Muslim insurgent group, peace is not necessarily around the corner.
Two separate incidents, both carried out by Muslim separatist groups, indicate that more than four decades of religious conflict are not over.
Malaysian troops are negotiating with about 100 men from the Philippines who have identified themselves as the 'royal army' of the Sulu Sultanate, which has a historic land claim to the area, say police.
The Philippines has been fighting a decades-long insurgency. But a cease-fire is holding and peace talks are advancing. What makes this possible is commitment from the top and the bottom: Leaders insist on moving ahead, and warring families want peace for their children.
US troops in the southern Philippines work to undercut militancy with projects such as better roads, fatter cattle, and a new school, which opened last week.
The Philippines massacre of 46 people on Monday on Mindanao appears to have been politically motivated, with fingers pointing to a powerful local clan.