South Korea’s defense chief on Wednesday blamed North Korea for sending a drone to spy on the US advanced anti-missile system deployed here, describing it as an attempt to acquire ground targets for future airstrikes.

Speaking to lawmakers at the National Assembly, Defense Minister Han Min-koo said the device, discovered last week by the South’s military, could carry biological weapons, warning against the possibility of a terrorist attack using drones.

The remarks came a day after the South Korean military announced the discovery of about 10 photos of a battery for the Terminal High Altitude Area Defense system in the device’s camera memory.

“I am certain that it was North Korea,” said Han. “I think there is sufficient reason (for the North to acquire the THAAD target through the drone). The drone appears to have engaged in figuring out the location and deployment of the THAAD battery.”

Han added, “As media reports suggested, the drone could inflict harm by mounting biological weapons and a shooting system.”

Describing the North Korean’s suspected drone activity as a “grave” violation of the armistice agreement between the two Koreas, the minister pledged the government would file a complaint against the North through the United Nations’ Command in Seoul.

The minister acknowledged that North Korea appears to have made advancements in drone technology with an expanded flight distance and a bigger fuselage, but stressed the drone was not developed enough to send images back to North Korea in real time.

His remarks came amid mounting concerns over North Korea’s use of drones for military activities. Although the South Korean military said the drone was designed for “surveillance,” analysts warned the North could turn the device into tools for terrorism.

“The military’s response is a typical example of complacency,” said Shin In-gyun, president of the nonprofit Korea Defense Network. “Drones could be developed into models that can carry toxic gas and anthrax. I don’t have to describe what would happen if the drone sprays toxic substances above Seoul.”

The drone’s payload has yet to be confirmed by the military, but Shin noted that as the device appeared to be an advanced version of a previous model, it could have carried up to 5 kilograms -- capable of delivering toxic materials to the South.

According to Seoul’s Joint Chiefs of Staff, the drone found last week used an advanced twin engine and was bigger than one the military recovered in 2014. Classified as a single-engine drone, the model was able to carry only 400 to 900 grams, capable of carrying a single grenade, the JCS analyzed.

Citing a former North Korean diplomat who defected to South Korea, the Washington Times reported in May that Pyongyang’s military has 300 to 400 attack drones capable of carrying biological and chemical weapons that could reach Seoul “within one hour.”

Analysts acknowledged that there are challenges in detecting and intercepting small drones with current surveillance and air defense assets, but stressed that the military has done little to address what they described an “imminent threat.”

After a North Korean drone was found to have flown over the presidential palace of Cheong Wa Dae and taken pictures of it in 2014, the South Korean military announced plans to ramp up efforts to purchase and develop low-altitude radars targeting drones.

The Army decided to acquire 10 RPS-42 radars from Israel, but has yet to complete the purchase. It also began development of an indigenous radar system, but the deployment is expected to take place at least two years from now.

“The North Korean drone threat is an imminent one,” said Shin. “The military doesn’t need to stick to the idea of purchasing radars from a specific country or developing its own indigenous model. It’s time to put all the options on the table.”

Some analyst cautioned the measure would result in massive wastes of taxpayers’ money for extravagant defense spending, criticizing it as the military’s attempt to avoid public embarrassment.

“We shouldn’t constrain ourselves when responding to the North Korean drone,” said Chun Young-woo, former presidential secretary for foreign affairs and security.

“It is rather South Korea who has more demand for drones. We should use more drones to detect and strike North Korea’s missile and nuclear threats. We could ask for understanding from the North about sending drones for surveillance purposes during the armistice.”

By Yeo Jun-suk (jasonyeo@heraldcorp.com)