Tensions escalated on Sunday as the USA army brought down the jet near Raqqa and Iran launched missiles at Islamic State targets in eastern Syria - the first time each state has carried out such actions in the multi-sided Syrian war.
The Islamic Revolutionary Guard Corps said that several "ground-to-ground, mid-range missiles" were fired from bases in West Iran's Kermanshah province.
It said the attack targeted "a command base. of the terrorists in Deir Ezzor", Syria's oil-rich eastern province.
The notorious ISIS claimed responsibility for the twin attacks at the Iranian parliament and the tomb of Ayatollah Khomeini in Tehran, in what would be the first time it has carried out a major terror operation on Iranian soil.
Iran has been a key backer of Syrian President Bashar al-Assad during the country's civil war and the IRGC has played a crucial role on the ground.
Out of the seven missiles fired at Islamic State (ISIS)-held positions in the city of Deir el-Zour, only two were believed to have hit their target.
Activists in Syria did not immediately have information about the Iranian-claimed strikes. However, it stopped short of directly blaming the kingdom for the attack, though many in the country have expressed suspicion that Iran's regional rival had a hand in the assault.
The Syrian military said that the jet shot down had been carrying out anti-Islamic State operations, and that its lone pilot was killed in the strike.
The attack also came as emboldened Sunni Arab states - backed by U.S. President Donald Trump - are hardening their stance against Iran.
Despite these efforts, a Syrian SU-22 warplane later arrived on the scene and dropped bombs near the US -backed rebels.
"IRGC warns takfiri terrorists and their regional and trans-regional sponsors that if the lowly and satanic measures against the Iranian nation are repeated, [our] revolutionary wrath. will send criminals to hell", the statement said.
"IDF sources have been saying the operational results of the launches were a lot less impressive than the noise the Iranian media was making about the launch".
Meanwhile, tensions between the U.S. and Iran have mounted since President Donald Trump took office, with the two countries imposing sanctions on one another last month.
"The SDF is getting big-headed", said the pro-Damascus military commander, a non-Syrian who spoke to Reuters on condition of anonymity.
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