However, there are serious concerns being expressed in the Pentagon that the US could be dragged into a wider regional conflict, not just with Syria but Iran.
Officials are privately worried that Iran's ongoing efforts to build an area of control stretching from Tehran to Beirut will eventually expand the US war by posing a security threat to US troops operating in southern Syria near the border with Iraq and Jordan.
In the last few weeks US forces have had to respond to Iranian backed Shia militias challenging US outposts and a garrison at At Tanf. The US military has recently expanded its presence in the area establishing several small outposts called "operating areas." These small bases are an addition to the main garrison at At Tanf where US troops are training local tribes to fight ISIS.
The US has also shot down a Syrian jet as well two Iranian made drones
in recent weeks.
This is all adding to a growing sense of concern that the war against ISIS in southern Syria might inevitably escalate to see the US fighting the Syrian regime as well as Iranian-backed forces.
The stated mission of the US is to expand the presence of American troops available to train local forces to fight ISIS. At the same time the US is backing the effort to defeat ISIS in Raqqa in the north, whilst also focusing on the Euphrates River Valley as a key target after ISIS leaders fled the city.
To date, encounters with Assad regime forces and the Iranian-backed militias have been characterized as self-defense. Defense officials say it would take a major policy decision from President Donald Trump to expand the mission to challenge them, but the worry is more confrontations are becoming inevitable.
US military officials believe the Iranian-backed militias as well as Assad regime forces are attempting to move deeper into eastern Syria. The US also believes Assad regime forces are pushing to reach the city of Deir Ezzor.
At the same time, Iranian militias are trying to open a transit route across southern Syria as part of what the Pentagon is informally calling a new "Shia crescent" of influence from Iran all the way to the Mediterranean. If that effort succeeds it would create a route for Iran to ship weapons and supplies to Hezbollah and other terror groups. US officials believe this would pose a new threat to both Israel and Jordan.
But the forces the US is training in southern Syria near where militias are operating are also likely to head east towards the Euphrates River Valley between Deir Ezzor and Mayadin. Intelligence reports have indicated that several senior ISIS operatives have fled Raqqa and moved into the valley between the two towns.
The US believes the area is becoming an increasingly important to ISIS with bomb making operations possibly centered there.
US officials say three top ISIS officials have been killed by the coalition around Mayadin. That includes the May 31 airstrike that killed Turki Al Bin'ali, the chief cleric of ISIS. In a news release announcing his death, the Pentagon called him a "close confidant of Abu Bakr al-Baghdadi" and a US official confirmed to CNN that Bin'ali moved in the highest circle of the organization. He was also linked to efforts to recruit foreign fighters and launch attacks "around the world."
The US also believes ISIS is continuing to work on developing both higher yield and miniaturized explosives that have been used on drones, as well as mustard agents in the Mayadin area.
As ISIS is forced into retreat, the potential flash points for confrontation between US-backed forces, Assad regime troops and Iranian militias are only likely to increase. This means that as the Trump administration weighs up whether to send more troops into Afghanistan, it is also going to have to make some tough decisions on the war against ISIS if the US wants to avoid being dragged into a wider regional war.