Over the past few weeks, a number of the thousands of foreign volunteers who flocked to join the fight against Russia have gone missing or have been captured.

Last week, two Britons and a Moroccan who were taken prisoner while fighting for the Ukrainian armed forces were sentenced to death in Russian-occupied eastern Ukraine, after being accused of terrorism.

This week, two Americans fighting with a group of foreign soldiers went missing in action near Kharkiv, Ukraine’s second-largest city, which is about 25 miles from the Russian border. Their families fear they have been captured, having disappeared after the platoon came under fire.