The news agency reported that missiles targeted the "headquarters and gathering centers of Takfiri terrorists supporting and building vehicle bombs". Iran is backing President Bashar al-Assad, while the U.S. is supporting a rebel militia and leading a coalition campaign against Islamic State.
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The missile attack was the first by Iran outside its own territory in almost 30 years, since the Iran-Iraq war of 1980-88.
Syria's six year long civil war has now evolved into an worldwide conflict during in many nations. On the one hand, Iran is making an unprecedented use of its weapons technology while on the other hand, it is targeting ISIS in supposed retaliation for the terror attack inside its own country. It is more likely to have been a warning to the enemies of the Iranian Regime; Israel, Saudi Arabia, and the US.
"The Guards" missile strike sends multiple messages, said Amir Handjani, a non-resident fellow at the Atlantic Council.
The missile attack came amid recent confrontations in Syria between US -backed forces and Iranian-backed pro-government factions.
The Revolutionary Guards said, according to the New York Times, the missile launches "targeted the headquarters and meeting place and suicide vehicle assembly line of ISIS terrorists" in the province of Deir al-Zour, where Islamic State group forces surround an estimated 200,000 people in a government-held section of the provincial capital of the same name.
Shiite-majority Iran and Sunni-majority Saudi Arabia have always been embroiled in a sectarian feud.
It also raises questions about how U.S.
The IRGC coordinated the attack with the Syrian government prior to launching missiles.
The president also put Tehran "on notice" in February after it launched a ballistic missile.
Iranian officials meanwhile offered a series of threats of more strikes, including former Guard chief Gen. Mohsen Rezai.
"They don't have the capability to engage in clashes with us for now and of course, we don't intend to involve in clashes with them but we are in permanent rivalry with them in different fields, including the missile sector", he said.