This is the first time since its 1980s war with Iraq that Iran has launched a major missile strike outside the country.
Iran's Islamic Revolution Guards Corps (IRGC) says its next "crushing response" to potential enemy missteps has already been planned days after it struck ISIL positions in Syria with missiles in revenge for its terror attacks on Iranian soil.
Iran is supporting the regime of Syrian President Bashar al-Assad with ground forces and advisors in coordination with Russian Federation.
The launch of surface-to-surface, medium-range missiles into Syria's Deir el-Zour province comes as Islamic State militants fleeing a USA -led coalition onslaught increasingly try to fortify their positions there.
Activists in Syria said they had no immediate information on damage or casualties from the strikes.
However, Spokesperson for the US Central Command Colonel John Thomas said Islamic State terrorists were not present in the Ja'Din village and that it was controlled by the Syrian Democratic Forces. Iran's last foreign missile strike is believed to have been carried out in April 2001, targeting an Iranian exile group in Iraq.
"The Saudis and Americans are especially receivers of this message", he said.
"We will retaliate against the terrorists and their supporters who martyred our people", the IRGC's second-in-command, Lieutenant General Hossein Salami, said after the Tehran attacks.
Iranian media has highlighted the missile attack as a success and the first by Iran outside its own territory in 30 years, since the Iran-Iraq war of 1980-88.
Iran's supreme leader Ayatollah Ali Khamenei today praised the "success" of Iraqi forces in the battle against the Islamic State group in Mosul. He has also criticized the nuclear deal between Iran and six major powers, including the U.S., that led to the lifting of most sanctions against Iran, in return for curbs on its nuclear programme.
But it was also meant to show that "Iran, in its fight against terrorism, needs missiles - and sanctions have no influence on its defence policies". "I have one message for Iran: Don't threaten Israel".
"Security cannot be traded and those who think they can provide their security by dragging extra-regional countries here are making a stupid strategic mistake", he said.
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