Who are the Syrian rebels?

Most people understand Syria like this:

Assad vs. rebels

Chemical weapons vs. whatever they can get

Russia vs. USA

As Americans, we hear "Civil War" and think of two sides locking horns with each other until one comes out on top. Syria's war isn't like that. There are literally hundreds of groups struggling for power. They merge and split like cells under a microscope.

Rebels aren't necessarily the "good guys." Sometimes, they are - in the words of President Trump - bad hombres. Mainly, they're operating in these 6 groups:

1. Free Syrian Army

These are defectors from Assad's military. Mainly Salafist jihadists, they pretended to be secular for juuuuust long enough to collect weapons from the CIA and Saudi Arabia. Turkey supports the FSA, while Russia opposes it.

Big slices of the FSA ended up quitting that group and joining the al Nusra front a few years ago. The al Nusra front was a Syrian branch of ISIS from 2012 to late January 2017. Al Nusra is now known as...

2. Tahrir al Sham

Just like the FSA, these guys are Salafist Wahabbist Jihadists who want to oust Assad and form a theocracy. (Know who else was Salafist Wahhabist? Osama bin Laden.)

Government estimates place Tahrir al Sham at 40,000 people strong - significant, given that it only started in late January of 2017. Though about 20,000 of ttheir fighters came from al Nusra, they now oppose ISIS (al Nusra's former parent organization) and operate instead as a branch of al Qaeda.

Tahrir al Sham opposes Russia, Syria, Iran, and the United States.

3. Liwa al-Aqsa (here's where things get complicated)

These guys started out as Sarayat al Quds, which was a subset of al Nusra (remember: al Nusra = ISIS).

Sarayat al Quds broke away from Al Nusra because al Nusra was growing too fast. It later joined Al Nusra again, but at that point, al Nusra was using the name Jabhat Fateh al-Sham. Then, these guys changed their name again, to Jund al Aqsa, and broke away yet again.

Just to keep things interesting, this group then changed its name to Liwa al Aqsa. Liwa al Aqsa consisted of roughly 2,100 fighters in February 2017. In that month, Tahrir al Sham (think: al Qaeda) attacked - and the group split in two. One chunk was absorbed into Tahrir al Sham, and the other became part of ISIS.

4. Ahrar al-Sham

Ahrar al Sham is made up of about 20,000 Salafist Jihadists. Saudi Arabia and Turkey fund them, since they oppose Iran and Russia. This group is allied with the Free Syrian Army.

These guys opposed Liwa al Aqsa when it still existed, and they're opposed to ISIS as well. They basically want the same thing: to control Syria under strict sharia law.

5. Ansar al-Sharia

This isn't one group, but a collection of groups that formed an alliance. Their end goal was controlling the city of Aleppo under a joint charter. Al Nusra was a member, as was Ahrar al-Sham.

This joint alliance went about as well as you'd expect. It started in July of 2015 and was defunct in early 2016.

This is not an exhaustive description of these groups, or of all the groups of importance in Syria. Add in foreign interference, and you'd have enough material to fill several books (Hezbollah, for instance, is sending fighters in from Lebanon to keep Assad in power by fighting against the Free Syrian Army and Ansar al Sharia).

Now you see why "provide weapons to the moderate rebels" is not a viable strategy. In a war being fought from all sides, among extremist Islamic groups, there is no clear desirable outcome.