The Air Force F-15 first intercepted the Iranian-made drone and shot it down as it continued to advance, the coalition said.
It was the second time this month that the US has shot down an armed drone in the vicinity of the camp at Tanf.
Russian Federation reacted angrily to the USA shootdown of the Syrian jet, which the Pentagon said was dropping bombs near the US-backed Syrian Democratic Forces, a mixed Kurdish-Arab militia fighting Islamic State. That is where US forces have been training and advising local Syrian Arabs for the fight against Islamic State militants.
The U.S. end of the line, located at the air command operations center in Qatar, remains open, Davis said, adding that the U.S. remains committed to using it.
Russian Federation also warned on Monday that it would treat US-led coalition jets in Syria that fly west of the Euphrates River as targets.
Dunford said there was still communications between a USA air operations center in Qatar and Russian forces in Syria.
Australia has deployed about 780 military personnel as part of the US-led coalition fighting in Iraq and Syria.
Tuesday's incident marked the third time the US has shot a pro-government aircraft from the sky within a month.
The SU-22 fighter bomber was engaged by an F/A-18E Super Hornet after it had dropped bombs near the US-backed Syrian Democratic Forces, the Pentagon said.
Al-Tanf is a strategic point near the Syrian, Iraq and Jordanian borders.
The two latest shoot downs, in addition to the one on June 8, has raised questions over whether the U.S.is getting drawn into a war with Russian Federation or Syria, rather than just with ISIS.
"In an email to NPR, Australia's Department of Defense says it will make a decision on rejoining the U.S-led air campaign in due course", NPR's Alison Meuse reports from Beirut.
The U.S. and Russian Federation established the line after Russian Federation entered Syria in September 2015 to support Assad to avoid deconflict operations and avoid unintentional conflict. Iran's Revolutionary Guard described the strike as revenge for Islamic State attacks on Tehran earlier this month that killed at least 18 people and wounded more than 50.
Last week another Iranian-made drone flown by pro-regime forces was targeted after it dropped munitions close to US and partner forces.
"The US" repeated combat operations under the guise of "combating terrorism' against the legitimate armed forces of a United Nations member-country are a flagrant violation of global law and an actual military aggression against the Syrian Arab Republic".
It was not known what exactly was hit and Iran has provided no details.
A mosque destroyed by US -coalition airstrikes in the northern Syrian city of Raqqa.
They are believed to be a threat to coalition forces in the region, he has said.