The UK's defence ministry says Russian forces are about 25 kilometres from the centre of Ukraine's capital Kyiv.

Attacks are continuing in a number of other cities including Kharkiv and Mariupol.

An airstrike on a military base near Ukraine's border with Poland killed 35 and injured more than 100.

Russia expert Matthew Schmidt from New Haven University told Mike Hosking there are signs Putin is arresting high-level officials in his security services.

“That might be a sign that the real nature of the war is getting through to him now, and he’s seeking scapegoats and that might be a sign that there’s weakness inside the court.”

Schmidt says Russia's doing what people knew it would: using size to control Ukrainian territory.

“Ukrainians are still maintaining a fighting spirit and still have the capability to bog down the Russians and defeat them over the long term in a guerrilla war.”

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