Listening to The News Agents yesterday, I heard a guest claiming that Putin killing Alexei Navalny was a sign of weakness. He was wrong. Putin learned from the fall of the USSR. The 1991 Soviet coup attempt would probably have succeeded if not for Boris Yeltsin. Putin, a fan of history (though with his own soin that distorts reality) is aware that if Yeltsin had been dealt with sooner, he would not have been present to help organise effective resistance against the coup. By killing potential rivals including the late Boris Nemtsov, he is ensuring that there is no figurehead to take advantage of any instability, should it happen. Remember that this almost came to pass when The Wagner Group marched on Moscow last year.
At least his rivals are not dismembered while still alive, unlike what has happened with our friend and ally, Saudi Arabia. The ally we have continued to sell arms to despite their use in Yemen.