Kim Yo Jong slammed South Koreans who doubted the authenticity of North Korea’s reported weekend spy satellite test in a statement Tuesday, while warning Pyongyang could soon silence critics by testing nuclear weapon reentry vehicle technology in an unprecedented long-distance launch.

The North Korean leader’s sister also confirmed for the first time that Sunday’s spy satellite test involved the launch of two rockets, matching ROK and Japanese assessments, but also criticized the detection capabilities of South Korea’s military at length.