In the crash’s aftermath, Azerbaijan has unleashed rare and stinging criticism of Russia, with the country’s president saying Moscow’s response has caused “surprise, regret and rightful indignation.”

U.S. officials say Russia could be behind a passenger plane crash in Kazakhstan that left at least 38 dead Wednesday, but Russia is denying any involvement.

Russia and Kazakhstan have tried to calm speculation about the cause of the Azerbaijan Airlines plane crash, following claims that it was shot down by Russian air defence systems.On Thursday, Moscow urged calm as its foreign minister said it would be wrong to draw conclusions before an investigation into the crash was complete.

Azeri President Ilham Aliyev says Vladimir Putin’s apology isn’t enough, in a confrontation that shows Moscow’s waning influence over former Soviet territories.

The extraction of flight data from the Brazilian-made Azerbaijan Airlines plane that crashed in Kazakhstan last month was completed at a lab run by Brazil's air force, according to a statement released by the entity on Monday.

Azerbaijan’s leader on Monday accused Moscow of carrying out a “cover up” over a passenger jet crash last month that claimed 38 lives, as relations sour between the two neighbors.