This may be another major why this is good for Putin. Iran and Russia are currently disputing ~$8 Trillion of offshore oil and gas deposits in the Caspian Sea.
https://oilprice.com/Energy/Energy-General/How-Iran-Was-Swindled-Out-Of-32-Trillion.html
The Caspian Sea is actually a lake because it is enclosed completely by land and not at sea level. Revenue from lakes is split by all countries that border them.
From 1921 to 1991 the USSR and Iran split Caspian Sea oil revenue 50/50 with a formal amended agreement in 1924. After the dissolution of the USSR in 1991, the four former Soviet states: Russia, Kazakhstan, Turkmenistan, and Azerbaijan claimed a share and they all split the revenue 20% each.
Recently, Iran gave Russia control of nearly all their oil and gas for 50 billion/year over 5 years. Per the agreement, the Russians were to invest massively in Iran. There are no clauses holding Russia accountable if they don't, so they don't hold up their end of the bargain and have Iran over a barrel.
Russia then dug a channel from the Caspian Sea to the Volga River and reclassified the Caspian Sea as an actual sea. If it's a sea, then the countries get a 12 mile territorial waters plus 200 mile exclusive economic zone.