Ukraine is facing a ‘hammer blow’ of 50,000 Russian troops in Kursk – can they hold out?

The Russian army's multiple rocket launcher Solntsepyok fires towards Ukrainian positions in the Kursk region - (AP)

After months spent occupying a swathe of territory in Russia in the wake of a daring summer assault, Volodymyr Zelensky has claimed that Ukraine is now engaged against a force of 50,000 troops amassed by Vladimir Putin in the border Kursk region.

The Ukrainian incursion was the largest on Russian soil since the Second World War and succeeded in taking Moscow – and even Kyiv’s closest allies – by surprise.