The problem is that now Russia backs Iran and Assad.
Russia has a long relationship with Syria. It goes back deep into the cold war days at least the 60s ad 70s. It may go back farther. I don’t know.
As for Iran, we can thank Jimmy Carter for that.
The Shah was a proud ally of the West, and particularly the United States. Today we understand the dynamics of terrorism, the sects of Islam and how they fight amongst themselves. The Shah had to rule with a firm hand, but he was by no means the type of guy Hussein was (for instance).
Western culture had become common there. Women could walk around in Western clothing. They could attend school and college. It as an enlightened nation.
People immigrated to the United States. It was a cordial relationship.
In walks Jimmy Carter, he saw the couple of thousand (supposed) political prisoners, and he determined the Shah had to go. Carter had all the savvy of a six year old on this subject. It didn’t occur to him that Iran was by far the closest nation to the United States in the region outside of Israel.
The Shah had stuck his neck out to befriend a Western nation, from that region. Carter betrayed him. Carter, a supposed Christian, hated the man so much that when the Shah needed treatment for cancer, he refused him and his family an entry Visa into the United States.
On top of that, Carter didn’t realize that he was sending a clear message to every single ally of ours, that at a moments notice the leadership in the U. S. could change and they could become an instant adversary of ours.
Think what a chilling damper that would be for a leader in the region who might have wanted better relations with the U. S. Who would stick their neck out after that? Who would anger their own people, then risk having the U. S. turn on them too without cause?
We handed Russia Iran on a silver platter.