The scale of the attack underlines the importance of the next phase in this war

The dozens of drones fired at Ukraine by Russia is a sign of the crucial juncture we have reached in the invasion.

Vitali Klitschko, the mayor of Kyiv, described it as the “biggest” such attack he had seen, with airstrikes and missiles also used on other cities. It was the fourth such attack on the capital in little more than a week, although Mr Klitschko said all the drones aimed at the city had been shot down.

Moscow has stepped-up its long-range assault ahead of an expected Ukrainian counteroffensive. The drone attacks followed a lull in the wave of Russian airstrikes.

Russia is due to commemorate Victory Day on Tuesday, which marks the victory of the Soviet Union over the Nazis in the Second World War. It is an important occasion in the country and has only increased in significance for Vladimir Putin and the Kremlin since Moscow started its invasion of Ukraine last February.

Mr Putin has constantly sought to compare the government of Ukraine’s president Volodymyr Zelensky to the Nazis throughout the invasion, desperately trying to create the impression of a moral crusade.

If the invasion was only initially due to last weeks or a few months, the fact that we are almost 15 months in and Kyiv and the rest of Ukraine are still fighting – with the help of weapons from Western allies – will be a source of great embarrassment to Mr Putin.

Indeed he has increasingly turned his ire towards Nato, the US, the UK and the EU in recent months as the invasion has faltered – stuck in the bloody fighting in the south and the east, particularly around the eastern city of Bakhmut.

Occasions such as Victory Day have been the time when Mr Putin has looked to bolster support at home for his war, but Moscow has cancelled or curtailed some of the huge military parades that normally accompany Victory Day across the country.

Western nations say this is partly out of security concerns, partly for fear of publicising Russia’s heavy casualties in Ukraine, and partly because Moscow has lost so much military hardware in its grinding winter offensive.

Ukraine believes that Mr Putin is seeking a battlefield win to mark Victory Day, with Bakhmut the target. Kyiv has said it intends to prevent Moscow from doing so.

In a sign of the difficulties Moscow has faced, the head of the Wagner Group mercenary force – which has been at the forefront of the push for Russian forces to take Bakhmut – threatened in recent days to withdraw his forces over a lack of ammunition and support. While Yevgeny Prigozhin appears to have subsequently withdrawn that threat, saying that he has been assured supplies are arriving, it has only added to the pressure on Russia’s military and defence officials.

Both Russia and Ukraine realise the importance of this next phase of the war, as Moscow looks to advance and Kyiv aims to push it back and reclaim the territory it has lost. Mr Zelensky – always shrewd when it comes to communications – broke with tradition to mark Victory Day on Monday, getting in ahead of Mr Putin.

“Recalling the heroism of millions of Ukrainians in that war against Nazism, we see the same heroism in the actions of our soldiers today,” Mr Zelensky said.

It could prove to be an important week.