Zelenskiy says air defences must quadruple to halt Russian advance

The Ukrainian president, Volodymyr Zelenskiy, has said he expects Russia to step up its offensive in the north-east and warned Kyiv only has 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. Zelenskiy said Russian troops advanced between five to 10km (3-6 miles) along the north-eastern border before being stopped by Ukrainian forces, but added that fighting in the region could be the "first…