A U.S. F-15E Strike Eagle fighter jet shot down an armed “pro-Syrian regime” drone advancing on coalition forces in Southern Syria at approximately 12:30 a.m. on Tuesday.

The drone was identified as a Shaheed-129 that displayed “hostile intent and advanced” on coalition forces at the At Tanf combat outpost used to train partner Syrian forces in the fight against the Islamic State (ISIS).

The U.S.-led military coalition said in a statement that the shoot down occurred where another pro-regime drone dropped munitions on June 8 before it was also shot down.

“The F-15E intercepted the armed UAV after it was observed advancing on the Coalition position. When the armed UAV continued to advance on the Coalition position without diverting its course it was shot down,” the statement said.

The shoot down comes two days after the U.S. announced it shot down a Syrian regime fighter jet on Sunday after it dropped bombs near U.S.-backed Syrian Kurdish forces advancing on ISIS’s stronghold of Raqqa. That incident angered Russia, which intervened in the Syrian civil war on Syria’s behalf in 2015 and has a hotline with the U.S. to deconflict airspace and make sure their air forces don’t collide mid-air.

Russia announced on Monday it was suspending the hotline, but the U.S. said it was still functioning as of Monday morning.

The coalition implied the hotline was still working as of Tuesday morning.

“There is a de-confliction mechanism in place with Russian forces to reduce uncertainty in this highly contested space and mitigate the chances of strategic miscalculation. Given recent events, the Coalition will not allow pro-regime aircraft to threaten or approach in close proximity to Coalition and partnered forces,” the statement said.

Chairman of the Joint Chiefs of Staff Marine Gen. Joseph Dunford urged calm on Monday, calling talk of “World War III” unproductive.

“The worst thing that any of us could do right now is, would be to address this thing with hyperbole,” he said during an appearance at the National Press Club in Washington, DC.

“An incident occurred, we have to work through the incident, we have a channel to be able to do that,” he said.

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 Russia or Syria, rather than just with ISIS.

But the coalition said the move was defensive.

“The Coalition presence in Syria addresses the imminent threat ISIS in Syria poses globally. 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,” it said.

“The Coalition has made it clear to all parties [publicly] and through the de-confliction line with Russian forces that the demonstrated hostile intent and actions of pro-regime forces toward Coalition and partner forces in Syria conducting legitimate counter-ISIS operations will not be tolerated,” the statement read.

“The Coalition calls on all parties to focus their efforts on the defeat of ISIS, which is our common enemy and the greatest threat to regional and worldwide peace and security.”