3 mins 40 secs into this Sub Brief video China assisted Iran to develop the 500 ton Fateh-class submarine here https://youtu.be/7Ku2cOKXyZU and below. The mainly indigenous Fateh's small size and stealth makes it ideal for the narrows and shallow waters of the Persian Gulf.
The first Fateh was commissioned in February 2019 and it constitutes a threat to the much larger USN SSGN and surface ships that are currently visiting the Persian Gulf. 7:45 describes Fateh's weapons.
Sub Brief's"Captain Jive" 10:40 provides specs, as well as Iran's intention to build 20 Fatehs. The Fateh's range will permit it to sail into the Arabian and Red Seas and (with refueling) into the Mediterranean. This all means a threat to Israel's nuclear armed Dolphin subs.
14:10, a Fateh is being built for landlocked Caspian Sea service against competitors that may one day, again include Russia.