On June 8, USA officials reported that a drone likely connected to Iranian-supported Hezbollah forces fired on US -backed troops and was shot down by an American fighter jet.
The U.S. -led coalition is providing close air support to the Kurdish-led Syrian Democratic Forces as they fight to retake Raqqa, the capital of the IS group's self-styled caliphate, where the 2015 Paris attacks and other foreign plots have been hatched.
"The armed pro-regime Shaheed-129 UAV was shot down by a U.S. F-15E Strike Eagle at approximately 12:30 a.m. after it displayed hostile intent and advanced on Coalition forces", according to a statement issued by Operation Inherent Resolve, the USA -led coalition fighting ISIS.
"As a precautionary measure, Australian Defence Force strike operations into Syria have temporarily ceased", the military said.
"Australian Defence Force protection is regularly reviewed in response to a range of potential threats", the Department of Defense said.
It has six fighter jets based in the United Arab Emirates that strike targets in Syria and Iraq.
The downing of the regime jet led Moscow to say it would sever a vital hotline it uses to communicate with the United States coalition to avoid mishaps in Syria's increasingly crowded and complicated battle-space.
The news from Australia, one of the coalition partners fighting ISIS in Syria, was described as a blow for the USA, putting it in a "very hard position" at a critical time as the battle to liberate the ISIS stronghold of Raqqa continues.
But even if neither Russian Federation nor the United States wants to get dragged further into war, they could be "chain ganged" to their allies who are jockeying to control land taken from ISIS, said Stephen Biddle, adjunct senior fellow for defense policy at the Council on Foreign Relations. The U.S. needed to send a deterrent message or Syrian President Bashar Assad will continue to press his offensive across SDF-held territory. However, the ongoing operations in Iraq would remain unaffected.
The Russian threat on Monday to target with anti-aircraft missiles any USA aircraft flying west of the Euphrates River in Syria is part of the same intimidation strategy.
The shoot-down was near Tabqah - a Syrian town in an area that has been a week-long focus of fighting against Islamic State group militants by the SDF, as they surround the city of Raqqa and attempt to retake it.
Meanwhile the Syrian army and its allies are also closing in on Raqqa and last week the Syrian military reached areas controlled by the SDF, making clashes between the opposing alliances nearly inevitable.
The Russian military says the USA did not use the the deescalation cooperation utility even though Russian Air Force jets were in the vicinity at the time. Also, Iran fired several ballistic missiles Sunday night at IS positions in eastern Syria.
The development comes as tensions rise in Syria with Russian Federation and Iran sending USA warnings.
On Sunday, a U.S. Navy F/A-18 warplane shot down a Syrian Air Force Su-22 that had dropped bombs near Syrian opposition forces.
"It doesn't look like anyone now intends to deliberately escalate further, but when you've got these little skirmishes. the risk is that you can end up in an escalation by accident", said Sam Heller, a Syria expert at The Century Foundation.
The Russian plane was armed and flew "erratically", the official added, noting that the maneuvers were deemed unsafe due in part to the proximity of the aircraft.