Just three weeks after the drone strike in the Kremlin, another sign of vulnerability: The fact that a group of heavily armed men managed to enter Russia from Ukraine and stay there – according to the official Russian account – in heavy fighting for at least a day and a half, must indeed cause "deep concern" in the Kremlin (according to Putin's spokesman).
At least as unpleasant for the Russian leadership as this failure of its own intelligence services and troops is the fact that the attack was carried out by Russians, concealed by its propagandists.
These fighters are far from being able to overthrow Putin's regime; with their crude anti-imperial-ethnonationalist ideology, they are unlikely to find much appeal among the Russian population. But the arson attacks on war commissariats and railway tracks in the interior of the country show that this internal Russian front can become a real security problem for those in power. Actions such as the invasion of the Belgorod region embolden violent opponents of Putin and have a demoralizing effect on his supporters.
At the beginning of its war of aggression, the Russian leadership relied on its troops to be supported by pro-Russian Ukrainians. Now it is faced with the fact that it is being challenged on its own territory by Russians who are on the side of Ukraine.