Iran's Islamic Revolutionary Guards Corps (IRGC) says it has fired missiles at militants in Syria to punish the alleged ringleaders of a deadly attack on a military parade in the southwest of the country.
The IRGC said on October 1 that "a number of leaders and effective elements" behind the attack in the city of Ahvaz were "killed and injured" in the missile strikes in eastern Syria.
Their "logistical infrastructures and ammunition depots" were also destroyed, a statement added.
Iranian state media reported that at least four gunmen dressed in military uniforms opened fire during a September 22 parade in Ahvaz, the capital of Khuzestan Province, marking the start of the 1980-88 Iran-Iraq War.
Both the extremist group Islamic State (IS) and an Iranian ethnic Arab separatist umbrella group called the Ahvaz National Resistance have claimed responsibility for the attack that left at least 25 people dead, including IRGC members and civilians. State media said all the attackers died.
The IRGC statement said six ballistic missiles were fired from western Iran by the aerospace branch of the IRGC and seven drones were later used to target "takfiri terrorists," a term used in the past to describe Sunni Muslim militants.
It said the alleged militants were backed by the United States and regional powers.
"The terrorists used bullets and we gave them a reply with missiles," Brigadier General Amirali Hajizadeh, head of the IRGC's aerospace division, according to the Fars news agency.
"The security of the Iranian people is our red line and we will not be found wanting," he added.
The Iranian armed forces' chief of staff, General Mohammad Bagheri, warned of further operations to come.
"The first stage of avenging the Ahvaz terrorist attack is complete, and other stages of revenge are still to come," Bagheri said.
Fars reported that the attack targeted a camp near the town of Albu Kamal in eastern Syria.
Iranian media reported that one of the missiles carried the slogans "Death to America" and "Death to Israel."
The British-based Syrian Observatory for Human Rights said "heavy explosions" took place at dawn in the last pocket of Syrian territory under IS control near Albu Kamal, which is held by Syrian government forces and allied militiamen.
The U.S. military's Central Command confirmed that Iranian forces conducted "no-notice strikes last night."
"At this time, the coalition is still assessing if any damage occurred and no coalition forces were in danger," spokesman Sean Ryan said.
Last year, the IRGC said it targeted IS members in Syria with missiles after the extremist group took responsibility for twin attacks on Iran's parliament and the mausoleum of Islamic republic founder Ruhollah Khomeini that left 18 people dead.