Iran Update, June 1, 2023
Iran has been building and training forces to target and kill US personnel and expel US forces from Syria.
Some of the arms and training that Iran has provided to militias in Syria could also support transfers of advanced conventional weapons.
Iran is attempting to assuage Western concerns about its nuclear program, likely to preempt the upcoming International Atomic Energy Agency (IAEA) report that will detail Iran’s noncompliance with its nuclear safeguard obligations.
https://www.understandingwar.org/backgrounder/iran-update-june-1-2023
Chief of Iran-Russia Joint Chamber of Commerce Hadi Tizhoush Taban said fhat Russia invested $2.7 billion in Iran's oil industry - about 45% of the total number of investments into Iran (October 2021-January 2023). The share of national currencies in the trade between two countries grew up to 60%.
https://twitter.com/Gerashchenko_en/status/1665096895901966344
https://www.mei.edu/publications/diagnosing-irans-emerging-pivot-toward-russia-and-china
A comment: This is not actual investment, its just getting around sanctions, selling russian oil under Ayatollah flag