BEIRUT: Whether thanks to hesitation, poor planning or a total lack of strategy, U.S. forces have been frozen out of eastern Syria, with Iran and the Syrian regime gladly seizing the initiative and securing a foothold on the Iraqi border. Remote, sparsely populated and seemingly unremarkable, the area around Al-Tanf on the Syria-Iraq border has become increasingly strategic, as the militant group Daesh (ISIS) prepares to make its last stand in Syria’s east.

It is in this desert outpost that the United States has been training Syrian rebels, apparently with a view to expand north and put a physical U.S. presence in between pro-Iran militias in Iraq and the Daesh-held Euphrates valley in Syria.

From here, Washington believed, a Sunni Arab force could be built up to rid the area of Daesh and deny the space to Iran and the Syrian regime.

Tehran and Damascus, however, have pre-empted the U.S. plan and, despite three recent airstrikes on Iranian-backed militias, pro-regime forces Friday managed to circumvent the troops at Al-Tanf and reach the Iraqi border.

Now U.S. forces and their rebel allies are hemmed in, with the route to the Euphrates valley blocked and Tehran now boasting an uninterrupted land corridor of influence that stretches all the way from Iran to Lebanon.

It is a strategic defeat for Washington. But, says Sam Heller, fellow at think tank The Century Foundation, the U.S. project along the Iraqi border never seemed particularly promising or viable in the first place.

“I don’t think that this was a race that they could have won,” he tells The Daily Star. “Not now, short of a major injection of U.S. troops, which I don’t think there’s a lot of political appetite for.”

Resources in Al-Tanf were thin. As few as 300 Syrian rebels were present there, alongside some 150 U.S. military personnel.

“That’s enough guys to die but not enough guys to do anything,” says Adam Garfinkle, editor of The American Interest and a Fox Fellow at the Foreign Policy Research Institute.

Belatedly, the U.S. seems to have realized that an injection of manpower and resources into this eastern area is to its advantage.

Syrian rebels said Wednesday that the U.S. has sent more special forces into the area, delivered weapons to its partners there and expanded out of Al-Tanf toward Zakf, about 60-70 kilometers to the northeast.

Meanwhile, CNN reported that a High Mobility Artillery Rocket System was moved into Al-Tanf from Jordan, greatly increasing the U.S. forces’ firepower.

It is likely too little too late.

Garfinkle says the Trump administration’s obsession with defeating Daesh in its Syrian stronghold Raqqa, where a U.S.-backed force is battling the militant group, has distracted it from the theater of lasting significance, eastern Syria, control of which will have implications all over the region.

And now Iran and the Syrian regime have the initiative and access to Iraq from Syria for the first time in three years.

For Iran and its allies, the symbolism of this breakthrough has been huge.

Iranian media circulated images of head of the Revolutionary Guard’s elite Al-Quds Force Qasem Soleimani praying alongside Afghan militiamen on the border, a message of defiance to the U.S. and those attempting to stop Tehran from having continual land access to the Mediterranean.

Such access has long been feared by Iran’s enemies, but Ellie Geranmayeh, senior policy fellow at the European Council on Foreign Relations, says its importance shouldn’t be overblown.

“Anyone looking at this issue and the significance of the land corridor needs to bear in mind that Iran already has good access,” she tells The Daily Star.

Yet it is perhaps significant that high-level talks between officials from Syria and Iraq, both largely dependent on Iranian support, were held in Baghdad Wednesday on border security and fighting Daesh.

In terms of battling the militant group, where Iran, the Syrian regime and the U.S. go from here is uncertain. Pushing deeper into the Euphrates River valley and Deir al-Zor, which are “denser and likely to be better defended by [Daesh] than some of these more peripheral and remote areas,” is not necessarily a fight the Syrian regime and Iran-backed forces want to engage in now, according to Heller.

And occupying an area wrought with ethnic, tribal and sectarian considerations is no easy task. “Managing the territory after a military victory is a huge responsibility and test for all sides,” Geranmayeh says.

“We shouldn’t underestimate nor overestimate Iran’s capacity.”

However, once battles raging elsewhere are concluded – such as in Deraa and Raqqa – eyes will quickly turn east and troops and resources will be freed up for the flashpoint border area.

If tensions continue to heat up in this desert region, confrontation between Washington and Tehran could be around the corner.

“In terms of what happens moving forward, I am a bit concerned that this is potentially a hot spot where U.S. forces and Iranian-backed forces could get into tit-for-tat exchanges,” Geranmayeh says, “and that could escalate.”