Moscow has been learning from its mistakes that compromised its offensive in Northern Ukraine, a senior official from the United States Department of Defense said. The news comes as Ukrainian President Volodymyr Zelensky announced Russia has now started its assault on Eastern Ukraine.

“It appears as if they are trying to learn from the failed lessons of the north where they didn’t have proper sustainment capabilities in the area they were about to operate,” the unnamed Pentagon official told CNN.

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Over the last few days, the United States has noticed the movement of heavy equipment to East and Southern parts of Ukraine. This heavy equipment included “command and control enablers, heavy artillery and rotary aviation support”, the official explained.

United States National Security Advisor Jake Sullivan had previously warned that Moscow would not retract its troops from Kyiv and instead reposition them and prepare for another assault.

Zelensky, in a video address released on Monday, said that the assault on Donbas had already begun. “Now we can already state that the Russian troops have begun the battle for the Donbas, for which they have been preparing for a long time”, Zelensky said.

A senior US defense official told Associated Press that there are now 76 Russian combat units, known as battalion tactical groups, in eastern and southern Ukraine, up from 65 last week.

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Before shifting focus to Eastern regions, Russia served a blow to Lviv, a city located on the Western borders of Ukraine and a key checkpoint for arms trade with NATO countries and other allies of Kyiv.

Moscow said its missiles struck more than 20 military targets, including ammunition depots, command headquarters and groups of troops and vehicles, according to reports from Associated Press.