Numerous broadcasts of North Korea’s external radio service and some of the country’s jamming of foreign radio stations has been off air in the last few days, according to several reports.

Voice of Korea, which broadcasts in several languages on shortwave to audiences outside of the country, missed many of its scheduled transmissions on July 20 and July 21.

On a typical day the station uses as many as eight transmitters simultaneously to beam its programming around the world, but on July 20 a radio monitor in Bulgaria noted only had two on the air at any one time. A day later, on July 21, the station had between two and seven transmitters on air simultaneously depending on the time.

Voice of Korea has gone through periods in the last few years when it regularly missed some transmissions. The radio station never acknowledged any problems leaving the cause unknown. Speculation has centered around engineering work for the installation of new transmitters or power supply problems.

Also on July 20, radio monitors in the U.S. noted the broadcast of South Korea’s KBS Hanminjok Bangsong on 6015kHz shortwave could be clearly heard without jamming.

North Korea typically jams this station by broadcasting noise over the top of its signal so listeners in the DPRK cannot hear the programs. (You can read more about North Korean radio jamming in an article I wrote for NK News.)

A day later, monitors also noted some of the transmissions of Echo of Hope and Voice of the People, both South Korean government broadcasts aimed at North Korea, were also free of jamming.

Monitoring will continue of the next few days.