Afghanistan could become a terror base because it couldn’t directly be accessed by US air assets, and most of its neighbors were, pre-9/11, reluctant to give the US access to their air space for strike missions. So the US resort was to $2m a pop Tomahawk missiles (vs $25K a pop bombs with JDAM kits if fighters could fly through Pakistan). Whereas, thanks to its Mediterranean coastline, the US can strike Syria from carrier and air bases in the region 24/7/365.
There is also the IDF right next door. Who already seized the high ground in the Golan Heights.
In the last two days they have destroyed multiple sights of munitions. Including trucks traveling through Syria loaded with shells/munitions/explosive materials.
The BBC was showing the remnants of a convoy of trucks this morning(I watched on YouTube). There were burned out trucks with unexploded ordinance laying around on the ground. The IDF had hit this convoy the day prior.