The treatment of Pussy Riot, three of whose members have been sentenced to two years in a Russian prison camp for carrying out a peaceful protest, tells us much about the man who, one way or another, stands behind that verdict – Vladimir Putin.

For let there be no doubt: Russia's President could have influenced, and almost certainly did influence, this insane sentence.

Hiding behind the pretence that Russian courts are independent is nonsense. Putin commented recently he hoped the court would make a "correct decision", and it is impossible to imagine the judge writing her verdict without checking exactly what the boss meant by that. So this is Putin's verdict. It is appalling, and decried around the world.

Putin has shown he does not really care about his international image. Freeing the three women would have brought him instant kudos abroad. Instead he has scored an astonishing own goal.

He cares only about his image inside Russia, where few people have much sympathy for the women. Nationalists implored him to "defend Russian values" (allegedly under attack by Pussy Riot).

Churchmen were incensed by the women's performance in a cathedral and successfully turned the trial into a kind of medieval inquisition, in which the accused were essentially found guilty of blasphemy. But above all, the verdict is a political statement.

As the judge remarked in her verdict, the sentence was intended to "caution others" – in other words it is one more spike in the armour that Putin is erecting around the Kremlin as protests against his rule grow.

It is 100 days since Putin was re-elected for his third term as president, and we can now see clearly how he intends to govern. All talk of compromise with the opposition has been swept away.

It is a risky strategy. He may feel he can cope easily with a few thousand protesters in Moscow squares – people he sneers at as puppets of Western governments. But now the protesters have a new cause to champion - three young women (two of them mothers of small children) languishing in a prison camp, for nothing worse than a crazy performance in a cathedral. It could be Putin's biggest mistake.

l Angus Roxburgh is author of The Strongman: Vladimir Putin and the Struggle for Russia.