Iran's Revolutionary Guard Corps (IRGC) announced that it has launched several missiles at ISIS positions in Syria's Deir Az Zor province in retaliation for two deadly attacks in Tehran. Deir Az Zor is a province that links ISIS's de-facto capital, the Syrian city of Raqqa, with territory controlled by the group in neighboring Iraq.
ISIS claimed responsibility for the June 7, 2017, attacks on Iran's parliament and the Mausoleum of Ayatollah Khomeini that left 17 people dead and more than 50 wounded. Within a few days, the Iranian security forces announced that they had killed the alleged mastermind of the Tehran attacks and also carried out multiple arrests, rounding up people suspected of aiding the attackers.
The Revolutionary Guards has declared that "the spilling of any innocent blood" will not go unanswered and Iran had also put the blame for the Tehran attacks on Riyadh, saying Saudi Arabia was "promoting terrorist groups" in Iran. An IRGC statement carried on its website warned Islamic State militants and their "regional and international supporters" that similar retaliatory attacks would target them as well if another assault on Iran occurs. Iranian television showed footage of the missiles being launched into the night sky.
The firing of the missiles came hours after Supreme Leader Ayatollah Ali Khamenei met with families of Iranian forces fighting inside Iraq and Syria. Khamenei defended Iran’s role in Syria and Iraq, saying, "If the defenders of the holy shrine were not there, the enemy would have brought the battle to our streets by now." He also vowed that Iran would "slap its enemies" in honor of the victims' families, including those killed in Syria and Iraq.
The missiles attack took place also just hours after Iran held a joint naval exercise with Chinese warships in the Straits of Hormuz.
"Medium-range missiles were fired from the (western) provinces of Kermanshah and Kurdistan, and a large number of terrorists were killed and weapons destroyed," the IRGC said in a statement published on its Sepah News website on June 18, 2017. The IRGC used the term Takfiri to describe ISIS.
There was no report what was the type of the missiles that the IRGC used in the attack, but there is a high probability that they used Iranian-produced "Shahab-3" missiles. The original Shahab-3 missile is nearly identical to the North Korean No-Dong 1 missile. The range is likely about 1000 km but varies widely depending upon the weight of the payload. The Shahab-3 missile is primarily effective against large, soft targets (like cities). Since July 2003, the missile is believed to have been in operational use.
Iran’s ambassador to the UK, Hamid Baeidinejad, praised the missile strikes: "Missile attacks against ISIS military base in Syria manifested the will and capacity of Iran to fight against terrorism and security threats."
Mohsen Rezaee, a former head of the Revolutionary Guards, also reacted on Twitter, saying, "This is the beginning of taking revenge from ISIS. A bigger slap in the face is yet to come. The supporters of terrorists should take heed of Iran’s message of strength."
The UN Security Council prohibits Iran from undertaking any activity related to ballistic missiles that could deliver a nuclear warhead and prohibits foreign powers from assisting Iran in developing its ballistic missile program in any way, a ban that remained in place under the terms of the July 14, 2015, nuclear deal.
The US has put Iran "on notice" after it test-fired a new ballistic missile in February 2017. President Trump's previous National Security Adviser Michael Flynn has said the Trump administration was taking a stand over the test "that put American lives at risk." Iranian defense minister Hossein Dehghan confirmed reports that Tehran launched a medium-range ballistic missile, but said the test did not violate a UN Security Council resolution that bans Iran from developing missiles that can carry nuclear warheads.
This was the first operational use of mid-range missiles by Iran since the war with Iraq, which ended in 1988. The firing of the missiles is a major strategic development. The formal target was ISIS, but the message was far beyond.
In the context of the war in Syria: Iran is a key ally of the Syrian government of President Bashar al-Assad, alongside Russia and the Iranian-backed Hezbollah movement of Lebanon. Iran has been providing advisers, fighters, volunteers, militias, weapons, and money, but it is the first reported ground-to-ground missile attack from Iran into Syria since it descended into a civil war in 2011.
In the wider geopolitical context, it was a message to the United States and its allies: Israel, Saudi Arabia and other Sunni countries that Iran can hit targets all around the Middle East.