Ukraine: The Worst Is Yet To Come, US Officials Fear

US intelligence officials have warned that Russian attacks on Ukraine's major cities will likely escalate in the coming days, as an 'isolated' Putin grows increasingly frustrated with the slow pace of the invasion.

As the war enters its sixth day, the majority of Ukraine's cities, including the capital, Kyiv, and second-largest city, Kharkiv, remain under government control despite coming under heavy bombardments from advancing Russian troops.

The UK Ministry of Defense said that a 'strong Ukrainian resistance' has helped counter the Russian offensive, however defence sources have given a bleak outlook for what could happen next.

Russian military (Alamy)

'They have been slowed and they have been frustrated by their lack of progress on Kyiv, and one of the things that could result is a reevaluation of their tactics and the potential for them to be more aggressive and more overt in both the size and the scale of their targeting of Kyiv,' one defense official told CNN on Monday, February 28.

Another warned that while Ukraine had inflicted significant losses on Russia in the early phase of the war 'from a purely military/tactical standpoint, Russia has the manpower and firepower to take Kyiv. No question.'

Concerns of a possible 'second wave' of Russian attacks unleashing greater numbers and firepower come as a now 40-mile long convoy of Russian troops continues to approach Kyiv, with intelligence sources reporting that the capital city is likely to be encircled and laid under siege, causing the potential for a major humanitarian disaster should its residents lose access to food and other supplies.

In its latest update the MoD said that it had seen signs that Russia was already changing its tactics, stating: 'Russian forces have greatly increasing their use of artillery north of Kyiv and in vicinities of Kharkiv and Chernihiv. The use of heavy artillery in densely populated areas greatly increases the risk of civilian casualties.'

Vladimir Putin (Alamy)

The warning comes as a rocket attack in Kharkiv yesterday killed 'dozens' of civilians, with hundreds more injured.

US officials have also claimed the difficulties that have arisen so far during the invasion have led Russian president Vladimir Putin to become more isolated and poorly informed about the reality of the situation on the ground.

CIA Director John Brennan told NBC News: 'This was just such a bad, bad miscalculation on Putin’s part. He’s never faced something like this before... He’s suffered two black eyes, a bloody nose and a series of punches. He is being crippled on the battlefield and the financial front, and he has no good options.'

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