The Azerbaijan Ministry of Defense on Thursday condemned what it described as "slanderous" statements from Iranian Army Ground Forces Commander Kioumars Heydari, marking the latest indication of rising tensions between the oil-rich neighbors. Heydari claimed that members of the Islamic State (ISIS) fought on behalf of Azerbaijan and are still present in the country, a statement Azerbaijan asserted is baseless and completely unacceptable. This came a day after Azerbaijani security agencies announced they are investigating an "terrorist attack" following gunfire aimed at a lawmaker with strong anti-Iran views, injuring him at his home. Relations between Azerbaijan and Iran, which has a significant Azerbaijani population in its northwest, have soured in recent months. In January, Azerbaijan closed its embassy in Tehran following what it described as a "terrorist attack" that killed the embassy's security chief.