An RAAF F/A-18F Super Hornets deployed in Syria. Picture: Evan Morgan

Moscow’s threat comes after the US downed a Syrian government military jet on Sunday.

The stark warning that coalition aircraft are now fair game marks a massive escalation of tensions between Moscow and the West.

Washington has warned it will retaliate if Russian forces prepare to take down a US aircraft.

It could lead to open conflict between Russia and the United States.

“As a precautionary measure, Australian Defence Force (ADF) strike operations into Syria have temporarily ceased,” a defence spokeswoman said in a statement on Tuesday.

“ADF personnel are closely monitoring the air situation in Syria and a decision on the resumption of ADF air operations in Syria will be made in due course,” she added.

Alongside Australia, the UK, Denmark, the Netherlands, France, Germany, Jordan and Iraq are part of the US-led coalition combating IS in Syria and Iraq.

The US has said it has “repositioned” its aircraft used in the Syrian conflict to “ensure the safety of our aircrew”.

An F/A-18A Hornet prepares to depart on a mission from Australia's main operating air base in the Middle East.Source:Supplied

The latest stoush between with Putin over Syria began dramatically on Sunday when the US shot down a Syrian jet in countryside south of Raqqa, a stronghold of IS.

In six years of civil war that has ravaged Syria, it was the first time the US has shot down one of the country’s planes.

The US military said the Syrian jet had dropped bombs near rebel Syrian Democratic Force (SDF) fighters on Sunday. The US backs the SDF.

“In accordance with rules of engagement and in collective self-defence of coalition-partnered forces, [the Syrian jet] was immediately shot down by a US F/A-18E Super Hornet,” a coalition statement read.

But Damascus has said the jet was carrying out a “combatant mission against ISIS terrorist organisation”.

The action was a “flagrant aggression” that confirmed the US’ “real stance in support of terrorism,” Syria’s military said.

The US says it was protecting rebel Syria Democratic Forces (SDF) which are fighting against IS to regain cities in Syria.Source:AP

Theoretically, coalition forces and Russia have the same goal in Syria — to rid the country of IS.

But they are going about it in very different ways which has seen Moscow and Washington regularly clash.

Russia backs the Assad Syrian government regime, while the US wants Assad gone and has backed rebels.

On Monday, Russia said it was suspending a military hotline to the US designed to avoid collisions in the skies above Syria.

Indeed, it accused the US of failing to pick up the phone to warn them about Sunday’s attack.

But there was a much more ominous threat from Moscow. That any coalition jet west of the Euphrates river, that bisects Syria, was now in danger of being shot down.

An Australian F/A-18A Hornet is seen refuelling from a USAF KC-10 tanker during coalition operations over Syria and Iraq.Source:Supplied

Russia’s deputy foreign affairs minister, Sergei Ryabkov, said the US strike “has to be seen as a continuation of America’s line to disregard the norms of international law.

“What is this if not an act of aggression? It is, if you like, help to those terrorists that the US is fighting against, declaring they are carrying out an anti-terrorism policy.”

Moscow stopped short of confirming it would shoot down Australian or any other coalition jets. Rather it raised the possibility there were now grounds to justify just such a course of action.

“A threat for those jets may appear only if they take action that poses a threat to Russian aircraft,” Mr Ryabkov said.

Russia has warned coalition aircraft not to cross west of the Euphrates river in Syria.Source:Supplied

The Russian foreign ministry detailed what equipment might now be at risk.

“All kinds of airborne vehicles, including aircraft and UAVs [unmanned aerial vehicles] of the international coalition, detected to the west of the Euphrates river will be tracked by the Russian SAM systems as air targets.”

The ADF said that operations in Iraq will continue as normal.

The US said Russia might want to think twice before locking on to one of its jets.

“We do not seek conflict with any party in Syria other than ISIS, but we will not hesitate to defend ourselves or our partners if threatened,” Navy Captain Jeff Davis, a Pentagon spokesman, said on Monday..

An F/A-18F Super Hornet from No. 1 Squadron in the skies over Iraq.Source:Supplied

Syria-based journalist Alaa Ebrahim told Russia Today, a news service which generally takes a pro-Moscow view, said that Washington might be looking to ensure the Syrian government wasn’t part of any liberation of Raqqa.

“The US is trying to draw boundaries in the Syrian conflict and red lines for the Syrian army not to cross them,” he said.

British Prime Minister Theresa May called on Russia to reactivate the hotline to “reduce the chance of misunderstandings over what is a crowded airspace”, Reuters reported.

US officials are trying to calm the escalating situation and said they wanted to relaunch the “deconflcition’ hotline.

The link is a regular phone line staffed on the US side by a Russian-speaking officer and has been used daily since its inception.

In an appearance at the US National Press Club, Marine General Joseph Dunford, chairman of the Joint Chiefs of Staff, said US and Russian interests would both be served by avoid direct hostilities in Syria.

“The worst thing any of us could do right now is address this with hyperbole,” Dunford said.

“I’m confident that we are still communicating between our operations centre and the Russian Federation’s operations centre. I’m also confident that our forces have the capability to take care of themselves.”

Australia’s Air Task Group consists of 300 personnel, six F/A-18 Hornets, an E-7A Wedgetail Airborne Early Warning and Control aircraft, and a KC-30A Multi-Role Tanker and Transport plane.