BEIRUT — Islamic State group militants destroyed the landmark ancient Tetrapylon and parts of the 2nd century Roman theater in Syria’s historic town of Palmyra, the government and opposition monitoring groups said today.

Maamoun Abdulkarim, the head of Syria’s antiquities department, said the militants destroyed the facade of the second-century theater along with the Tetrapylon, a cubic-shaped ancient Roman monument that sits in the middle of the colonnade road that leads to the theater.

Satellite imagery obtained by the Boston-based American Schools of Oriental Research show extensive damage to the Tetrapylon.

DigitalGlobe satellite imagery also shows damage to the theater facade.

IS militants recaptured the ancient town in December from government troops — nine months after they were expelled in a Russia-backed offensive. During their first stay, IS destroyed other ancient temples including the Temple of Bel.