Sunni extremists in Iraq have occupied what was once Saddam Hussein’s premier chemical-weapons production facility, a complex that still contains a stockpile of old weapons, State Department and other U.S. government officials said.

U.S. officials don’t believe the Sunni militants will be able to create a functional chemical weapon from the material. The weapons stockpiled at the Al Muthanna complex are old, contaminated and hard to move, officials said.

Nonetheless, the capture of the chemical-weapon stockpile by the forces of the Islamic State of Iraq and al-Sham, known as ISIS or ISIL, the militant group that is seizing territory in the country, has grabbed the attention of the U.S. […]