A U.S. think tank said it has detected signs that North Korea had prepared for a second military reconnaissance satellite launch early this month, before canceling such a plan.

The Beyond Parallel website run by the Center for Strategic and International Studies(CSIS), citing satellite images from April 8, said on Tuesday that there were three vehicles at the VIP Observation Facility of the Sohae Satellite Launching Station. The facility is frequented by North Korean leader Kim Jong-un to observe launches and engine tests.

Stating that the area typically hosts communication, broadcast, and tracking vehicles prior to launches, the website assessed that the North is presumed to have initially planned for a launch. It also mentioned ten vehicles spotted in the courtyard of the administration and security headquarters.

However, by April 10, there was only one vehicle left in the area, suggesting a sudden postponement, with the website saying the presence of the vehicle implies that preparations continue for an anticipated launch in the near future.

There was also no indicator of an imminent launch in images of the coastal launch pad from April 8 and 10, where the first Malligyong-1 satellite was launched last November.