A fresh round of U.S. airstrikes on facilities used by Iran’s Islamic Revolutionary Guard Corps (IRGC) in Syria killed several proxy fighters associated with the regime, the Pentagon said Sunday. The targets included a training facility and a “safe house,” Defense Secretary Lloyd Austin said in a statement. The casualties mark a “significant escalation” for the U.S. in the region, according to The Washington Post, after a number of attacks by Iran-backed groups in recent weeks injured U.S. troops both in Syria and in neighboring Iraq.