Eight days ago, a convoy of 17 buses carrying 300 to 500 fighters and their families left the eastern side of the country after a truce was reached between surrendering ISIS fighters and Syrian government forces, which are backed by Hezbollah.
The US has objected to the truce, and in the days since the convoy departed, US aircraft have targeted 40 vehicles and any members of the convoy who stray too far from the main group.
"Whether it's to evade by foot or to relieve themselves, if they make it far enough out there for us to strike, then we will," US Army Col. Ryan Dillon told Foreign Policy.
Last week, US airstrikes destroyed a bridge and made a road impassable, and the convoy has since been stuck between the Syrian cities of As Sukhnah and Abu Kamal, the latter of which is on the border with Iraq.
Six of the buses have turned back toward territory held by the Syrian government; the rest have been resupplied by trucks coming from Syrian government territory.