The head of the South Korean government agency for defense research and development said Tuesday the uncrewed aerial vehicles seen in footage released by North Korean state media do not seem to be South Korean.

“These UAVs do not seem distinctly South Korean, although there are similar-looking ones among commercial kinds as well as those developed (by the military),” Lt. Gen. Lee Kun-wan, president of the Agency for Defense Development, said in response to questions from lawmakers.

“They have the shape of the UAVs that North Korea sent to the South in 2014, and the Sky-09 UAV used in the North. So it’s hard to tell which,” he said.

“All we have access to is this footage released by North Korea, so any further analysis is kind of limited.”

He added that the UAVs in the North Korean news footage appeared different than those developed by the Agency for Defense Development.

In an announcement Friday, the North Korean Foreign Ministry claimed that South Korean UAVs carrying anti-Kim Jong-un leaflets had trespassed into Pyongyang three times this month.

Building on the claims, the North Korean leader’s sister Kim Yo-jong on Monday said that the South Korean military was “clearly behind the UAV incident in Pyongyang.”

The South Korean military said it would not confirm the claims raised by North Korea.