There are few voices who speak with greater moral authority or clarity on Russia than Natan Sharansky.

The former refusenik spent nine years in Soviet prisons in the 1970s and 1980s, becoming an iconic figure in the Jewish world and beyond. His strength and eventual release helped free 2 million Soviet Jews.

Since then, in his books, writing and speeches he has retained a focus on his former home country.

As chairman of the Jewish Agency for nine years from 2009 he was also responsible for smoothing the path of many fellow immigrants to Israel from Russia.

So when Natan Sharansky warns that Russia’s actions now threaten to block Jewish emigration once again — in effect, returning to the Soviet era when Jews were unable leave — the world should listen.

Sharansky believes that Russian Jews are being used as a tool by Putin to attack new Israeli prime minister Yair Lapid’s outspoken criticism of the invasion of Ukraine — taking a far more openly critical line than his predecessor, Naftali Bennett.

The Russian leader has seized on the importance of the Jewish Agency to Israel, accusing it of high treason — the same crime of which Sharansky was convicted.

20,000 Russian Jews have left for Israel in recent months — but a further 80,000 are seeking to leave, and there are grave worries that they will be, in effect, held hostage in Russia.

If Putin sees the fate of Russian Jews as a weapon he can deploy to pressurise an opponent of the invasion, he will not hesitate to use them as such. We are in dark times, indeed.