Fighting in Syria escalated on Sunday as the United States downed a Syrian warplane that targeted ground forces fighting ISIS, while Iran launched missiles at ISIS targets in eastern Syria, The New York Times reported .
— Robert Satloff (@robsatloff) June 19, 2017 
The incident with the Syrian plane began after the U.S.-backed rebel fighters, called the Syrian Democratic Forces, were attacked by what the American military called “pro-Syrian regime forces.” Several of the rebels were injured.
U.S. warplanes buzzed the pro-Assad forces in an attempt to scare them away from the rebels, and contacted the Russian military to defuse the situation.
Despite these efforts, a Syrian SU-22 warplane later arrived on the scene and dropped bombs near the U.S.-backed rebels. After trying to warn the aircraft away using emergency radio, American forces shot down the SU-22.
While the U.S. insisted it wasn’t targeting Syrian positions, it also pointed out that the rules of engagement allow the military to provide for the “collective self-defense” of its allies.
“The coalition’s mission is to defeat ISIS in Iraq and Syria,” a statement from the U.S.-led coalition fighting ISIS in Syria said. “The coalition does not seek to fight Syrian regime, Russian, or pro-regime forces partnered with them, but will not hesitate to defend coalition or partner forces from any threat.”
Since the shooting down of the Syrian plane, Russia has stopped  coordination with the U.S. in Syria and threatened to shoot down any planes from the U.S.-led coalition that it detects west of the Euphrates river.
Also on Sunday, Iran’s Islamic Revolutionary Guard Corps said it fired a number of mid-range missiles from western Iran at ISIS targets in eastern Syria. The missiles flew over 500 miles over Iraqi territory, and are the first mid-range projectiles launched by Iran since its war with Iraq, which ended in 1988.
According to the IRGC, the missiles “targeted the headquarters and meeting place and suicide car assembly line” of “ISIS terrorists” in Syria’s Deir al-Zour Province. ISIS forces currently surround an estimated 200,000 people in the province, which is held by the Syrian government.
— Nadav Pollak (@NadavPollak) June 19, 2017 
The Times noted that “Iranian-backed Shiite fighters are also believed to be trying to link up with Iranian-backed militias in Iraq and establish a supply corridor that runs from Syria to Iraq and, eventually, to Iran.” This would effectively give Iran a land corridor  to the Mediterranean and pose a direct threat to Israel.
*US downing a Syrian plane is signif., but can be managed
*IRGC firing ballistic missiles is huge and needs a WH response
— Nadav Pollak (@NadavPollak) June 18, 2017 
[Photo: ABC News / YouTube ]