The American-led U.N. Command in South Korea on Tuesday accused North Korea of planting land mines near a truce village inside the Demilitarized Zone that divides the two Koreas.

Much of the border, one of the world's most dangerous flashpoints, is strewn with land mines and laced with barbed wire. But South Korean media said no land mines had been planted in the area of the truce village of Panmunjom until North Korea placed an unspecified number there last week.

The U.N. Command said in a statement that it "strongly condemns" any North Korean action that jeopardizes the safety of personnel in the DMZ.

It said it wouldn't speculate on why North Korea placed the mines there. Yonhap news agency, citing an unidentified South Korean government official, said the North apparently planted the mines to prevent front-line North Korean soldiers from defecting to South Korea via Panmunjom.

North Korea's state media didn't immediately respond to the U.N. Command statement.

Panmunjom, jointly overseen by North Korea and the U.N. Command, is where an armistice that ended the 1950-53 Korean War was signed and is now a popular tourist spot for visitors from both sides.

Under the Korean War armistice, the two sides are barred from carrying out any hostile acts within or across the 2.5-mile-wide DMZ. Still, they have accused each other of deploying machine guns and other heavy weapons and combat troops inside the zone.

More than a million mines are also believed to be buried inside the DMZ. North Korean mines occasionally have washed down a swollen river into South Korea, killing or injuring civilians. In August 2015, land mine blasts maimed two South Korean soldiers and caused tensions between the two Koreas to flare.

The U.N. Command statement came a day after U.S. and South Korean troops began annual drills despite North Korean threats to retaliate against the exercises, which it says are a rehearsal for an invasion. This year's drills come at a time of intensified animosity between the rivals over the defection of a senior North Korean diplomat in London and a U.S. plan to install a sophisticated missile defense system in South Korea.

On Tuesday, South Korean officials said three North Koreans who were found on a boat off South Korea's western coast earlier this month have expressed a desire to resettle in the South. More than 1,000 North Koreans have defected to South Korea each year between 2012 and 2015.