Russia-Ukraine war live: three reportedly killed by Ukraine drone attack on air base deep inside Russia

Three Russian military personnel reportedly killed when a drone attacked an airbase near Saratov, 450 miles south-east of Moscow

Here are some of the latest images we have received from Ukraine.

The UK’s Ministry of Defence says Russian troops have focused mainly on constructing defensive positions along many sections of the frontline in Ukraine since October.

Minefields only present an effective obstacle for trained troops if covered by observation and fire.

A major challenge for the Russian forces will likely be a shortage of surveillance assets and trained personnel to effectively monitor large areas of the new minefields.