Thailand’s army is warning that it may have to“exercise the right of self-defense” in response to continuing incidents it blames on Cambodia in which Thai soldiers patrolling along the two countries’ border have been wounded by land mines. The Thai army says a sergeant was patrolling the border with seven other soldiers Tuesday morning when he ”stepped on an anti-personnel landmine covertly planted by the Cambodian side, resulting in severe injuries to his left ankle.” The incident and the Thai reaction indicates the precariousness of the ceasefire that took effect July 29 with the aim of ending five days of armed clashes over disputed territory along their border.