U.S. concerns over an imminent Syrian regime-Russian-Iranian axis attack on Syria's Idlib region are rooted in how the axis intends to carry out its attack. Those concerns gained added voice on Monday with a tweet from President Trump.



President Bashar al-Assad of Syria must not recklessly attack Idlib Province. The Russians and Iranians would be making a grave humanitarian mistake to take part in this potential human tragedy. Hundreds of thousands of people could be killed. Don’t let that happen! — Donald J. Trump (@realDonaldTrump) September 3, 2018



So why is the U.S. so worried here?

For one thing, U.S. intelligence sees evidence Bashar Assad will use chemical weapons in Idlib. Bolstering this suspicion is Vladimir Putin's strategic interests: He wants Assad to employ chemical weapons in order to degrade American credibility. Russia will try to present any chemical attack as the result of a western-supported conspiracy to blame Assad. While this deception is simplistic, it indicates that Russia both expects Assad to use chemical weapons and has given its tacit blessing for him to do so.

At the same time, because Idlib is a large province with numerous urban settlements, axis forces will indiscriminately use stand-off weapons in an attempt to break rebel formations without engaging in bloody street-to-street and house-to-house fighting. And because the axis has very little regard for civilian life, it will not use many forward observers to support the greater accuracy of strikes. That means a lot of air and artillery strikes saturating towns and killing a lot of civilians. Evidencing as much, over the past two days we have seen major Russian airstrikes on the western Idlib city of Jisr al-Shughur. These shaping operations indicate an imminent ground offensive to secure the city – which has strategic value for its position on multiple Idlib crossroads.

Finally, we can't really prevent the offensive. United Nations efforts to prevent a massacre are a very unfunny joke, and there is rightly no appetite for a military showdown with Russia. That leaves the U.S. in a position of providing limited intelligence and logistical support to more-moderate allied rebels in Idlib, and striking Assad should he use chemical weapons. Also, Turkey might previously have acted to counter the axis incursion, Turkish President Recep Tayyip Erdogan's strategic realignment towards Moscow means that he'll now grudgingly accept the offensive.

In short, the U.S. is upset about a slaughter it can do little to prevent. That said, Trump can and should take what's about to happen as new evidence for why Russia should receive no respite from sanctions. And if Assad does use chemical weapons, the president should order the annihilation of much of the dictator's air force.