President Volodymyr Zelenskyy had pleaded for military aid, and the West responded.

The stage was set for a spring offensive in the latest phase of Ukraine‘s efforts to liberate its lands.

However, weeks have passed since modern tanks and weapons were delivered to Ukraine, providing invaluable time for Russia to put together robust physical defences.

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Why has Mr Zelenskyy delayed the start of the operation, and will that delay compromise the effectiveness of their spring offensive?

Although fighting continued throughout the winter, poor weather affects warfare – 60-tonne tanks cannot operate off-road effectively unless the ground is dry, so any offence over the winter was constrained.

Instead, Mr Zelenskyy used the winter to persuade the West that Ukraine had the ability and determination to prevail over the much larger Russian army – all he needed were the tanks, weapons and ammunition required to do the job.

The West obliged.

Ukrainian forces then needed time to become familiar with their new Western military equipment. Alongside this, Ukraine has been recruiting and training tens of thousands of new recruits, with much of that training being conducted abroad.

However, any delay has also helped Russia prepare and build more robust and comprehensive defences, and disrupt Ukraine’s plans.

The destruction of the Khakovka dam this week protected Russia’s flank in Kherson from Ukrainian assault. But, the Ukrainian military will probably have anticipated that eventuality, since the Russians had set demolition charges on the dam since their occupation early last year.

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What dam explosion evidence proves

Russia very likely to inflict significant casualties during a Ukrainian counter-offensive

Preparations for a major military offensive are complex – they need to be conducted in secret, involve multiple options, include deception plans, and then it has to be weighed up as to which is most likely to succeed.

The Ukrainian military has proven very adept at pushing Russian forces out of half of Ukrainian territory once held, and there is an air of expectation that Ukraine’s counter-offensive could be decisive.

The West might think that the Ukrainians will roll back the Russian forces, but that is only one possible outcome. Russia is – after all – a superpower, and has significant resources available.

It has had time to establish formidable defensive obstacles, and Ukraine will expect to suffer three times as many casualties on offence compared to the Russians on defence.

Russia is very likely to inflict significant casualties on Ukraine, and if the tide swings in Russia’s favour they might even decide to mount their own counter-offensive to exploit Ukrainian vulnerability.

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How Zelenskyy faces difficult call of weighing up risks of an offensive

Military operations are always risky, prone to unpredictability, and are highly dependent on initiative and momentum.

The anniversary of D-Day was earlier this week – the first phase of the WWII operation to liberate Europe. Germany knew that the allies planned to attack, but like the Russian forces awaiting the Ukraine offensive, they did not know where, or when the attack would occur.

On the eve of D-Day, then prime minister Winston Churchill dined with his wife Clementine, and observed that by supper the following evening, 20,000 soldiers could have perished on the beaches of Normandy.

Even with decades of military and political experience, Churchill felt the heavy burden of responsibility on his shoulders.

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Did Russia ‘blow the dam’ early?

Mr Zelenskyy will know the risks and will want to ensure plans are complete and ready before commencing offensive action. However, in war, 90% often has to be “good enough”.

The difficult call of whether to go ahead is a mix of objective and subjective metrics which relies heavily on experience and judgement.

Mr Zelenskyy has proven to be an outstanding wartime leader, but he has very limited military experience. He was a politician for three years – and prior to that, he was an actor and comedian.

Although he has very capable military advisers, even they lack experience in this field.

The forthcoming Ukrainian offensive might well prove decisive. However, the stakes could not be higher for the nation of Ukraine or its leadership.

Little wonder that Mr Zelenskyy has taken some time to be satisfied that the potential benefits outweigh the huge risks.

The West will be hoping that this has been time well spent.