Blue House Denies Accusation They Flew Drones Into North Korea
I doubt the Lee administration flew these drones so it is likely civilians that flew them. Even if they are civilian drones, this shows North Korea has poor defenses against drones:
Cheong Wa Dae on Sunday reaffirmed that South Korea has no intention of provoking or irritating North Korea, after Pyongyang again blamed the South for drone incursions into the North and demanded an explanation.
In a statement, the Office of National Security at Cheong Wa Dae said, “The government once again confirms that it has no intention of provoking or irritating the North side.”
“The government will look into the latest drone incident through a joint military-police probe and promptly disclose its results,” the office said, also pledging continued efforts to ease inter-Korean tension and build trust.
On Sunday, Kim Yo-jong, the powerful sister of North Korean leader Kim Jong-un, called on Seoul to provide a detailed explanation, a day after the North Korean military claimed that the South violated the North’s sovereignty by sending drones in September and on Jan. 4.
You can read more at the link.

