Pentagon says no apparent progress by Russian forces

But some large cities are suffering serious bombings, according to a senior U.S. defense official.

A troop column moving towards Kiev remains about 20km outside the capital Kiev, where the official said civilians are facing more and more attacks.

The Russians continue to face fierce resistance in their attempt to take Kharkivin over Ukraine's second largest city and Mykolaiv, a southern town near the Black Sea.

However, invading forces have isolated Chernihiv in the north and Mariupol in the southeast, though the US says Ukraine is working to keep the lines of communication open with local leaders.

The defence official notes that both Russians and Ukrainians have used about 90% of their fighting power. More US-funded weapons are expected to arrive in Ukraine over the next 24 hours, he said, broadcast CNN.