Russia loses 500-600 troops in hostilities every day, while Ukraine's losses are a tenth of this figure, Defence Minister Oleksiy Reznikov has said in an interview with the BBC.
According to Reznikov, Russia may be trying to accumulate "forces, supplies and weapons" for an offensive from the regions it occupied in the south and east. Ukraine needed time to regroup and rearm.
"Spring is the best period for all sides to resume the movement. We understand that they will be ready to start, of course, we must be ready to start too," he said.
Ukrainian military intelligence chief Kyrylo Budanov earlier suggested that the hottest battles would take place in March. Ukraine has planned a major advance for spring.