The rocket that exploded Sunday outside the U.S. embassy in Baghdad is of a design trafficked by Iran and used by Middle Eastern terrorist groups.

While it is unclear who was responsible for firing or supplying the Katyusha rocket, weapons of the same type were seized by Yemeni authorities on an Iranian ship in 2013. Iran is known to support terrorist groups in the region both financially and with arms, and Iranian forces are known to field Katyusha rockets.