People watch a television news program reporting about DPRK's live-fire drills, at a Seoul train station in Seoul, the ROK, March 31, 2014. [Photo/icpress.cn]

SEOUL - An unidentified unmanned airplane fell in one of the five Republic of Korea (ROK)'s islands near the inter-Korean western sea border, Yonhap News Agency reported Tuesday, citing a government source.

ROK fires shells at DPRK waters after drills US-South Korea joint landing exercises in Pohang

The unmanned aerial vehicle crashed at around 4 pm Monday local time in the Baengnyeong Island, just south of the Northern Limit Line (NLL), or the disputed maritime border between the two Koreas, said the source.

The ROK's military took the pilotless airplane from the border island to identify where the unmanned aerial vehicle(UAV) came from.

The UAV, detected Monday, was the same kind of the one found on March 24 in Paju, 50 km northwest of Seoul, the ROK's capital.

The source said that the ROK's intelligence and military officials were probing whether the two airplanes came from the Democratic People's Republic of Korea (DPRK).

The DPRK conducted its live-fire drill Monday afternoon, firing around 500 rounds of shells and projectiles with its artillery and multiple-rocket launchers from its shoreline gun positions in the DPRK's southeastern region near the NLL.

Some 100 of them landed in ROK's waters 2-3 km south of the NLL, the scene of the recent inter-Korean naval skirmishes. In November 2010, the DPRK shelled the Yeonpyeong Island, one of the five border islands near the NLL, with its shoreline artillery, killing four people.

Amphibious assault vehicles of the ROK Marine Corps throw smoke bombs as they move to land on shore during a US-ROK joint landing operation drill in Pohang March 31, 2014. [Photo/Agencies]