Entering the city while letting most of the fighters escape would pave the way for a long partisan war, waged by guerrillas based in the mountains, where they are almost impossible to winkleout.
Its existence came to public notice just when, after a quarter-century of intermittent activity on the Labour back benches, Mr Robinson had become a Treasury minister in Tony Blair's new government, and not long after he, of all ministers, had been put in charge of a government effort to winkleout offshore tax havens.
Russia is finding it hard to winkle Chechen fighters out of their strongholds in mountain gorges in the south, where the fugitives from Grozny were heading this week.