Seoul’s Defense Ministry said Friday that the three drones, recently found in frontline regions, were “definitely” from North Korea, citing circumstantial evidence including their filming of South Korean military facilities.

Announcing the interim result of their probe, the ministry also said that it would form a scientific investigation team with civilian experts from Korea and the U.S. to confirm Pyongyang’s responsibility for sending the drones.

“Based on circumstantial evidence, the drones were definitely from the North. But for a clearer verification of the North’s responsibility, we need an additional scientific, technical investigation,” Kim Min-seok told reporters during a press conference.

The military authorities have discovered three drones so far in Paju close to the western Demilitarized Zone on March 24, on the border island of Baengnyeongdo on March 31 and in Samcheok close to the eastern DMZ last Sunday.

The authorities now plan to verify that the drones had come from the North, by analyzing data from memory chips containing “mission orders” and from the drones’ global positioning systems, which are expected to confirm where they took off and which routes they used to enter the South’s airspace.

The analysis process is expected to take one or two months, Seoul officials said.

One piece of circumstantial evidence was that the drones hovered around and filmed areas where South Korea’s military facilities were concentrated. They also found six fingerprints on the drones that didn’t match any on the registry of South Korean residents.

The ministry also said that given the size of fuel containers, engine displacement volume and other factors, the drones were capable of traveling between 180 km and 300 km, which made it “virtually impossible” for the drones to have come from China or Japan.

“Considering the weather conditions during their flights and the drones’ operational ranges, we judged that China or Japan couldn’t send the drones here,” said Kim. “On top of it, the drones are also totally different from unmanned aerial vehicles that South Korean civilians or military units have operated.”

The ministry also said that the drones contained components that were made in Korea, the U.S., Japan, China, Switzerland and the Czech Republic. The parts were all commercial items easily available in the general market.

It pointed out that model numbers of some components were intentionally deleted, a sign that the operators of the drones sought to conceal their origins.

The ministry also said that the camouflage color and patterns were “very similar” to the drones that the communist state revealed during a massive military parade on April 15, 2012, and North Korean leader Kim Jong-un’s visit to a military base on March 25, 2013.

Seoul is seeking to deal with this drone case in cooperation with the international community, as Pyongyang is likely to proliferate and export military drones, which would extend the security threat to the entire world.

Should it be confirmed that the drones illegally entered South Korea’s airspace, Seoul is poised to take “all measures available” including filing a complaint with the U.N. Command Military Armistice Commission for violating the Armistice Agreement.

“If North Korea is ultimately confirmed to be responsible for sending the drones, this would be a grave provocation and our military would strongly respond to that,” the ministry spokesperson said.

By Song Sang-ho (sshluck@heraldcorp.com)