More than 100 people have been left homeless by what has, until now, been a little-known armed Filipino group.
The self-proclaimed Royal Sultanate army sailed across the Sulu Sea to lay claim to Malaysia's eastern area of Sabah.
The group say they say are descendants of an ancient Sulu sultan who once ruled the land they are claiming.
Both the Philippines and Malaysia have called for the army to put down its weapons.
Al Jazeera's Steve Chao reports from Tanjung Labian, Malaysia.