It's been confirmed by a Swiss investigative NGO: Houthis from Yemen have takean part in the conflict between Ukraine and Russia. They're fighting on the frontline for Putin. 

The Swiss NGO Inpact (Investigations with impact) claims that the Yemeni Houthis have very close contacts with the Kremlin. The rebels are said to have been recruited into the Russian army through a company involved in arms trafficking. 

For months now, the United States has been accusing Russia of trying to supply arms to the Houthis in Yemen, rebels allied with Iran, reports 20 Minutes. For the past year, the rebels have been attacking ships in the Red Sea, increasingly disrupting international trade.

Lou Obsorn, a member of the NGO Inpact, points out that contracts between these mercenaries, most of whom are financially deprived, and the Russian armed forces go through a company linked to a Yemeni parliamentarian.