New satellite images taken on Sunday reveal that Iran has significantly accelerated engineering work around the craters created by last week’s U.S. strike on the Fordow nuclear facility.

The photographs show an excavator operating near one of the craters, as well as a sand conveyor removing soil from the site. The crater is near ventilation shafts that were targeted during the strike, and Iran appears to have made substantial progress clearing the area.

Images from two days earlier had indicated that initial engineering activity had begun, but the latest photos suggest that Iran is now working to reopen access to the underground facility.