An investigation into GPS disturbance felt in the west of the Korean Peninsula between April and May has led the International Telecommunication Union (ITU) to request North Korean assistance.

Sanjay Acharya, ITU’s head of PR revealed the news on Saturday, saying, “We have given a warning to North Korea about disturbing the operation of aircraft and vessels in South Korea. We have also requested emergency cooperation to find the source of the jamming suffered by South Korean base stations.”

North Korea is a member of both the ITU and International Civil Aviation Organization (ICAO).

RFA, which reported the news, added that disturbance was experienced by 609 aircraft from 10 different South Korean companies, and 48 aircraft from 22 different U.S., Japan and Chinese companies.