South Korea will develop a laser weapon system to shoot down drones sent by North Korea, the country’s defense ministry said Friday. This comes as Seoul has repeatedly alleged Pyongyang of building large drones that have greater range capability to be flown remotely using flight controllers.

The development of the laser weapon system is expected to begin by 2018 and it is expected to be ready by 2020, the defense ministry said, according to Yonhap News Agency. The technology will be part of its broader laser weapon system, the report added.

The North operates about 300 observation drones and around 10 machines capable of conducting attacks with weapons as per South Korea’s estimates, military officials told Yonhap. In the past, Seoul has captured several drones believed to be from the isolated country.

South Korean officials have expressed concern over such unmanned aerial vehicles sent by North Korea because they are difficult to detect by radar due to their small size and ability to fly low. Furthermore, it may prove challenging to shoot such low-flying drones with conventional anti-aircraft weapons even if they are detected.

North Korea, however, has denied ownership of the drones.

In 2016, the reclusive nation drew condemnation from several countries, including the U.S., following its series of nuclear and missile tests. On Sunday, the North’s leader Kim Jong Un said Pyongyang was in the final stages of preparing to test an intercontinental ballistic missile (ICBM).

“Research and development of cutting edge arms equipment is actively progressing and ICBM rocket test launch preparation is in its last stage,” Kim said in a televised New Year’s Day speech.

However, U.S. President-elect Donald Trump rubbished Kim’s claims saying that the North’s plans of developing a nuclear weapon “won’t happen.”

“North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the US. It won't happen!,” Trump tweeted Monday.