The U.S. military has released video from March 19, saying it shows its air strikes pounding an administration building at Mosul University in Iraq.
Media reports had said Islamic State was using a high-tech lab there to build bombs, chemical weapons and to secure uranium compounds.
Mosul is one of Islamic State's two major power centers in Iraq.
The video's release comes one day after U.S. President Barack Obama warned that IS must not be allowed to get its hands on a radioactive "dirty bomb."