The Russian government has warned against promoting “hypotheses” about the cause of the crash of a Russia-bound passenger plane in Kazakhstan, which killed 38 people on Wednesday.

Aviation experts have suggested that the Azerbaijan Airlines plane may have been hit by air defense systems over Chechnya, with pro-government media in Azerbaijan quoting officials who claim a Russian missile was responsible. Before crashing near the Kazakh city of Aktau, the plane had been diverted across the Caspian Sea, changing its route from Chechnya to western Kazakhstan.

Of the 67 people on board, 29 survived the crash. Azerbaijan declared a national day of mourning on Thursday for the victims, and President Ilham Aliyev expressed his sorrow, calling it a “great tragedy.”

In Moscow, Kremlin spokesperson Dmitry Peskov stated, “It would be wrong to put forward any hypotheses before the investigation’s conclusions. We need to wait until the investigation is completed.” The chief prosecutor in Kazakhstan confirmed that no conclusions had been reached yet.

However, some Azerbaijani media outlets are already suggesting that Russia may have shot down the plane, with channels airing expert interviews about the possibility of a Russian missile strike. One report claimed that the plane was hit by shrapnel from Russia’s Pantsir-S defense system.

Despite these allegations, the Azerbaijani government is proceeding cautiously, as any direct blame on Russia could strain relations. Officials have said that all versions of the crash are being investigated. The investigation committee, made up of Azerbaijani and Kazakh officials, is reportedly waiting for Russia to admit responsibility before taking further steps.

The inquiry is expected to examine why Russia did not close its airspace or allow the plane to land immediately, and instead directed it toward Aktau.

BBC