Western assessments of the ongoing war in Ukraine have said that the Russian military advance in Ukraine's east has been slower than planned and that Russian soldiers are suffering from low morale.

A senior US defence official has said the Russian offensive is going much slower in part because of the strength of the Ukrainian resistance.

The official said, "We do believe and assess that they are behind schedule in what they were trying to accomplish in the Donbas."

The official, speaking on the condition of anonymity, said the US believes the Russians are “at least several days behind where they wanted to be” as they try to encircle Ukrainian troops in the east.

As the troops try to move north out of Mariupol so they can advance on Ukrainian forces from the south, their progress has been “slow and uneven, and certainly not decisive in any, in any event”, according to this official.

Meanwhile, a British assessment of the ongoing war in Ukraine reports Russian forces suffering from "weakened morale".

The British defence ministry said that Russia “still faces considerable challenges” in fighting. The British believe Russian forces have “been forced to merge and redeploy depleted and disparate units from the failed advances in northeast Ukraine”.

The British analysts believe Russian forces that failed to take Kyiv at the start of the war have been redeployed without the time needed to properly rearm and restaff. They believe Russia hopes to reorganise its effort and shorten supply lines.

The ministry added, “A lack of unit-level skills and inconsistent air support have left Russia unable to fully leverage its combat mass, despite localised improvements.”

It has been reported?earlier that?Russian war efforts have not gone according to plans. Poor war strategies and battle tactics deployed by Russia have also been highlighted.

AFP earlier reported military analysts as saying that Russia made a mistake by sending in too few ground troops in the initial phase of the invasion and failing to get ground and air forces working in tandem.

Outlook earlier reported that Russian reliance on conventional armoured formations also led to Russian failures. Closely-packed tanks’ frontal assaults by Russia became soft targets for Ukrainian drones, resulting in the loss of 10 per cent of all Russian tanks pressed into the invasion of Ukraine by late March.?

(With AP inputs)