North Korea has identified the source of its COVID-19 outbreak, state media reported on Friday, stating an 18-year-old soldier and a five-year-old student contracted the virus in early April after coming into contact with “alien things” near the border with South Korea.

According to the Rodong Sinmun newspaper, health officials stressed the need to “vigilantly deal” with “alien things coming by wind” as well as “other climate phenomena and balloons” along the border. It is the first time the DPRK has identified the cause of its outbreak since announcing it in early May, in what one expert said was likely an attempt to shift blame to Seoul.