Almost eight weeks after Vladimir Putin sent troops into Ukraine, with military losses mounting and Russia facing unprecedented international isolation, a small but growing number of senior Kremlin insiders are quietly questioning his decision to go to war.

The ranks of the critics at the pinnacle of power remain limited, spread across high-level posts in government and state-run business. They believe the invasion was a catastrophic mistake that will set the country back for years, according to ten people with direct knowledge of the situation. All spoke on condition of anonymity, too fearful of retribution to comment publicly.

So far, these people see no chance the Russian president will change course and no prospect of any challenge to him at home. More and more reliant on a narrowing circle of hard-line advisers, Putin has dismissed attempts by other officials to warn him of the crippling economic and political cost, they said.