The US Air Force's E-8C, or JSTARS, was spotted in the skies over the metropolitan area, Aircraft Spots tweeted. The aircraft last flew over the country earlier this month.
The South Korean military said the communist country shot a fisheries official who was adrift in its waters to death and incinerated his body Tuesday. He went missing the previous day while on duty near the Yellow Sea border island of Yeonpyeong, Yonhap news agency reported.
Following the incident, the South Korean military tightened its defense readiness posture near the Northern Limit Line (NLL), the de facto inter-Korean maritime border.
Pyongyang admitted to the shooting and apologized Friday but claimed it set an object the official used to stay afloat on fire, not his body.
The flight also appears to have monitored North Korea's military movement ahead of the 75th founding anniversary of its ruling Workers' Party that falls on Oct. 10.
Satellite imagery and other multiple signs indicate that Pyongyang is preparing for a large-scale military parade in Pyongyang next month.
As a platform for airborne command and control, surveillance and reconnaissance, the E-8C is known to be capable of closely monitoring the movements of North Korea's troops and equipment, including missiles and artillery guns.
According to Aircraft Spots, the US Navy's EP-3E surveillance plane also conducted missions near South Korea's capital areas Friday.
The US also sent the C-146A Wolfhound aircraft from the Kadena Air Base in Japan to the Korean Peninsula on Friday, another aviation tracker, No callsign, tweeted.
This aircraft transports small teams of the US Special Operations Command. It can carry a maximum of 27 individuals or 2.7 tons of cargo, according to the US Air Force.