The South Korean military is conducting a massive search operation after detecting an unidentified individual near the northeastern border in Gangwon Province. 

The Joint Chiefs of Staff(JCS) said on Wednesday that the search operation is under way after an unidentified person was detected by the military's surveillance equipment near the heavily-armed border with North Korea.

The JCS said the military also issued a "Jindotgae Two" anti-infiltration alert in the region. 

According to a military official, a person from North Korea crossed over the border into South Korea on Tuesday night in what appears to be a defection.  

It remains unknown whether the person was a civilian or a soldier.