While it would be grand if this were the case, I’m afraid it doesn’t pass the smell test for one simple reason. The letter seems to have no purpose.
For example, if it was a diplomatic message to Russia, it would have some details, or refer to other meetings, or correspondence, etc. This is not a simple flight to make.
Even though the most direct route, over the Caspian Sea, would still involve a lot of prior permissions from other countries.
Otherwise, passing over Georgia or Azerbaijan would not be recommended, and the Turkmenistan-Uzbekistan-Kazakhstan route would be right out.
Ironically, the US would likely not interfere, being glad to see them go, but Obama’s foreign service is so ignorant, who knows what they might do.
See #17.