Ukraine’s president says air defences must quadruple to halt Russian advance as morale falls among troops

The Ukrainian president, Volodymyr Zelenskiy, has said he expects Russia to step up its offensive in the north-east and warned Kyiv has only a quarter of the air defences it needs to hold the front line.

Russian forces, which had made only moderate advances in recent months, launched a surprise assault in Kharkiv region on 10 May that has resulted in their biggest territorial gains in a year-and-a-half.