Two Russian power stations explode in huge fireballs after ‘Ukrainian drone strikes’ near border as Kyiv steps up plans for counteroffensive by WILL STEWART and JAMES REYNOLDS

The Belgorod region has faced intermittent drone and missile strikes from Ukrainian territory, albeit on a far smaller scale than the regular bombardment suffered by dozens of Ukrainian cities since Russia invaded.

But officials in Kyiv have also spoken of using sabotage tactics to cause fires and disrupt logistics in Russia.

Intelligence chief Major-General Kyrylo Budanov said knowingly in a recent interview that territory in western Russia was seeing many unusual explosions and fires.

‘Much of this is no accident… Something is constantly on fire [in Russia],’ he said, admitting that Ukraine was paying Russian saboteurs to damage or destroy key infrastructure and logistics equipment to slow down Moscow’s supply routes into eastern Ukraine.

‘Signalling equipment on railways, it lights up several times a day, on various highways constantly for two to three hours, sometimes for five to six hours, traffic gets suspended,’ Budanov added.

‘Clearly it doesn’t just happen like this…. I would put it this way: money works wonders.’

Ukraine has been building its forces over winter for a supposed spring counteroffensive, though there is no telling exactly when or where the attacks are likely to take place.

Prime minister Denys Shmyhal claimed last week the counteroffensive would start in the ‘near future’, while President Volodymyr Zelensky declared in a televised address this weekend that final preparations were being made.

‘The key is the constant destruction of the occupiers which is done to downgrade their logistic capabilities and any potential in the occupied territories. This is preparation for our active operations, this is counteroffensive work,’ he said.

But constant fighting in the Donbas region, particularly around the embattled city of Bakhmut, is thought to have absorbed a huge amount of both Ukrainian and Russian resources.

The Wagner mercenary group, which has been leading much of the Russian offensives in Bakhmut in recent months, claimed on Saturday to have captured more of the city – though Ukrainian defence officials maintain their forces have not been defeated.

And US intelligence documents leaked online appeared to suggest that Ukraine’s spring offensive could falter amid a lack of air defence ammunition.

The report also revealed American planners doubt Ukraine’s ability to mount a counterattack this spring, hit hard by ‘force generation and sustainment shortfalls‘

Russia has so far struggled to gain the upper hand in the skies, with Ukraine’s anti-air systems and fighter jets keeping Russian gunships at bay since the initial invasion.

But air force spokesperson Colonel Yuri Ihnat warned Russia might be able to push through in a matter of weeks if Ukraine’s air defences do not hold up, The Times reported.

He said: ‘If we lose the battle for our skies, the consequences will be critical. The Russians will smash every city just like they did in Syria.

‘Our nuclear power stations will be vulnerable too. And we will struggle to protect our frontline troops.’

At present, Buk and S-300 anti-aircraft missiles make up about 90 percent of Ukraine’s air defences.

The Soviet-era technology has been supplemented with Western-supplied HIMARS systems, a multiple rocket launcher system developed for the US Army in the 1990s.

Ihnat said the difficulty was with how to restock the weapons, which are only produced by Russia. He said Slovakia had been able to supply some to this point.

The ability to station and resupply Ukrainian surface to air missiles has been documented as one of Ukraine’s most immediate priorities in order to stave off Russian aggression.

After months locked in stalemate, the end of winter was expected to bring a new Russian offensive – but experts say the attack has ‘stalled’.