Following Sunday's incident, Russia threatened that USA -led coalition aircraft will be "followed by Russian ground-based air defense and air defense aircraft as air targets" if they are operating in Syrian airspace west of the Euphrates River while while Russia is on combat missions.
The actions of the United States and its allies were criticized by the Russian Foreign Ministry, and they were called by the Defense Ministry actually military aggression against Syria. The Russian ministry accused the U.S. of a "deliberate failure to make good on its commitments" under the deconfliction deal between the two forces.
Analysts were complaining Australia's move threatened to show disunity within the coalition and put the United States in a "very hard position, " though to be fair getting their planes shot down by Russian air defense would've put Australia into a pretty hard position as well.
That took place near the Syrian city of Taqba, which has been the focus of fighting as US -sponsored ground forces advance on the ISIS stronghold of Raqqa.
It could lead to open conflict between Russian Federation and the United States.
The last time the US downed a manned aircraft was in 1999, during the North Atlantic Treaty Organisation intervention in Serbia, when a US Air Force F-16 shot down a MiG-29.
The drone was approaching a small military base at the Syrian town of Tanf that U.S., British and Norwegian special operations forces use as a staging ground to train and equip rebel groups fighting the Syrian government and Islamic State militants.
The United States continues to maintain its end of the deconfliction line with Russian Federation for operations in Syria and would want to continue communications, US Department of Defense spokesperson Capt. Jeff Davis said in a briefing on Tuesday.
The move came after the U.S. shot down a Syrian Su-22 which, the Pentagon said, had bombed US-backed fighters battling IS near the town of Tabqa in Raqqa province.
Russia, a key ally of the Syrian regime, accused the US-led coalition of "complicity with terrorism" after the drone was downed in southern Syria.
On Tuesday, the US Central Command announced in a statement in downed an Iranian-made armed pro-Syrian regime drone that was nearing coalition partnered forces in At Tanf in southeastern Syria near the Iraqi-Syrian border.
The Russian Ministry of Defence called the downing of the plane "a cynical violation of the sovereignty of the Syrian Arab Republic" and "military aggression".
"They were threatening our forces on the ground", the USA official quoted by AFP said.
The last drone the U.S. says it shot down was also reportedly destroyed near Tanf after firing on coalition forces.
"The US is trying to draw boundaries in the Syrian conflict and red lines for the Syrian army not to cross them", he said.
Russia's Deputy Foreign Minister Sergei Ryabkov called the shootdown an "act of aggression", but the USA balked at the Russian threats and said it would continue to protect its interests in Syria.
"ISIS represents a threat to all nations", he said.
The Australian Defense Department presented the move as temporary, and insisted that strikes in Iraq will continue.
The U.S. -led coalition's actions were further complicated by Iran, which over the weekend launched strikes on ISIS targets in Eastern Syria - Iran's first missile strikes into the country.