One, the size of Iranian-controlled forces in Syria:
Iran appears to control most of the military forces available to the Assads. This force is better armed, trained and led than the Syrian military. The Iranian forces includes 3,000 Iranian personnel, 8,000 Hezbollah fighters (with more on call in Lebanon) and some 70,000 pro-Iran militias. About a fifth of these are foreign Shia mercenaries recruited, armed and led by Iranians. The rest are local pro-Assad militias that are equipped (and often paid) by Iran.
Note that Iran controls about 56,000 local Syrian militias in addition to their own troops. My guess is that the local militias are mostly static, meaning the mobile force Iran has is mostly the Shia foreign legion of 14,000, Hezbollah, and some portion of the Iranian contingent not advising and leading local defense militias.
And note that Syria controls something just under 80,000. But these are likely mostly static forces not reliable for anything more than local defense but must include some mobile force of technical branches like artillery and tanks, for example, rather than infantry.
Two, the scale of Iran's Middle East efforts which leads to a logical conclusion. The scale:
Iran responded to American criticism of Iranian aggression in Yemen, Syria, Iraq, Palestine and Lebanon by insisting that it had an obligation to aid these nations in their fight against American and Israeli threats. This justification is unpopular with most Iranians who want their government to pay more attention to real problems inside Iran rather than imaginary ones overseas.
Iran is spending more money than they really have in pursuit of wins in a number of countries. And the Iranian people are increasingly unhappy with the priority that the Iranian government places on those foreign victories.
Given that America is more focused on resisting Iran, it makes sense for America to increase the costs of Iran's foreign interventions by aiding the forces in those countries resisting Iran in order to increase the Iranian costs and give the Iranian people more reasons to be unhappy with their government.
The absolutely wrong approach would be to let Iran win their wars to enjoy the victory and then deal with their people with the freed up money and prestige of winning foreign adventures.
And given that Iran is trying to replicate their Hezbollah model of a pro-Iran state-within-a-state in Syria, Iraq, and Yemen, there is strong incentive to tear down Hezbollah which is the model for this objective.
Three, the future of Turkey in NATO:
The Turkish actions towards U.S. backed Kurds in Syria is but one of several actions Turkey has taken to cut its ties with Western nations since World War II. Turkey is a member of NATO because of that but NATO is edging closer to expelling Turkey. Not so much for Turkish moves in Syria, but because Turkey is becoming an ally of Russia. More to the point Turkey has ordered two Russian S-400 anti-aircraft systems and is in line to get over a hundred new F-35 fighters. The S-400 is not compatible with the NATO air defense system and the F-35s contain a lot of technical secrets the Russians would like to get a close look at.
So NATO is seriously thinking about kicking out Turkey? Huh. I guess my desire to pull our nukes out of Turkey is sound as is my worry about selling F-35s to
But I would certainly quietly pull out the nukes to prevent Erdogan from thinking he can seize them to get an instant nuclear deterrent (and yes, he probably couldn't use the weapons--but would we be sure?--but he'd at least have the material for making warheads. And I'd greatly reduce the capabilities of the F-35 we sell them. We should also introduce deliberate flaws in their stealth qualities during the production process that we know how to exploit.
And wouldn't it be nice to get a closer look at the S-400? Or do we already have that information?
And four, the new phase of the Syrian civil war:
The Syrian civil war is not over but it is entering its third phase. The first phase was in 2011-2 when the majority of Syrians turned against the Assad government. The Assads seemed doomed. But then the various rebel groups began spending more time fighting each other than the Assads. It got worse when ISIL showed up in 2013 and did not end until ISIL was crushed by the end of 2017. Now the factions are rearranging themselves for continued fighting.
With ISIL involved it was what I called a multi-war with actors focused on different objectives. Now with the defeat of the ISIL caliphate the fight is getting back to a basic question of whether Assad runs Syria.
This fits for my views that Assad did not win the war following the defeat of ISIL. I've read a lot of material that said Assad won--including some on Strategypage. But it seemed to me that Assad was very weak despite surviving the nadir of the war. How much more can Assad's supporters endure to prop Assad up? With ISIL no longer the monster in the closet inspiring his backers to hold the line, will they?
Read it all. More may stand out to you. These were just the pieces that I pulled out in particular.