Three Thai soldiers on patrol were wounded Saturday when one stepped on a land mine in territory along the border with Cambodia, Thailand’s army announced. The incident came just two days after the two countries reaffirmed their adherence to a ceasefire to end a brief armed conflict.

Thailand says it will lodge complaint against Cambodia for violating Ottawa Convention banning use of landmines.

Thailand and Cambodia have agreed to establish interim observer teams to monitor a fragile ceasefire that ended five days of deadly border clashes