STORY: A giant recruitment ad for Russia's Wagner mercenary force has appeared on the facade of an office block in north-east Moscow.Wagner is thought to have sustained heavy losses in the eastern Ukrainian city of Bakhmut, the longest, bloodiest battle of the war so far.It fights alongside Russian forces in the region and has sought to replenish troop numbers ahead of a potential Ukrainian counteroffensive.Seventeen stories high, the ad shows the group's logo and the slogans "Join the winning team!" and "Together we will win." Wagner boss Yevgeny Prigozhin said earlier this month that he aimed to recruit 30,000 new fighters by mid-May.Ukrainian and Western officials say Wagner is sending poorly prepared fighters to certain death.For months, Wagner has spearheaded Russia's push to take the small city of Bakhmut, now in ruins. Both sides have referred to Bakhmut as a "meat grinder."Prigozhin said his men's task there is to bleed the Ukrainian army dry.