Alexandra and Anna, both 27, were among a steady trickle of Russians at Ukraine's embassy in Moscow on Sunday who voiced shame, anguish and a sense of utter hopelessness after Russia's invasion, offering heartfelt apologies to Ukrainians.

The friends, who declined to give their surnames, believe their own brothers have been deployed with Russia's National Guard as part of the invasion following exercises in Crimea, one as a conscript and one as a contractor.

Russia annexed Crimea from Ukraine in 2014 and began a full-scale invasion of its neighbor four days ago, triggering a Western political, strategic, economic and corporate response unprecedented in its extent and coordination.