South Korea's Joint Chiefs of Staff said a North Korean man who crossed the border into South Korea early this week is a civilian and there were no additional border crossings at the time. 

In a Friday briefing, JCS spokesperson, Colonel Kim Jun-rak, refuted media speculation that the man may have been a North Korean soldier who attempted to infiltrate into the South or that there were more people observed trying to cross the border at that time.

Kim said only one North Korean defected across the eastern border in Goseong, Gangwon Province and expressed regret over unconfirmed reports suggesting there were more.

Meanwhile investigations are under way as to why the alarm did not go off when the man crossed over the barbed-wire fence, which is equipped with sensors.

One Joint Chiefs of Staff official said the JCS is checking the security system to determine whether it's properly working and if it is, why the sensors were not triggered.

After the inspection, the JCS will take follow-up measures if needed jointly with the Army.