Under pressure, Tunisia takes back hundreds of migrants trapped in border zone after tensions in Sfax

Hundreds of migrants pushed into no-man's land on Libyan border without basic necessities.
Spike in anti-migrant tensions in Tunisian port city of Sfax led to crackdown.
Migrant boat sank off Tunisian coast resulting in deaths, rescues and missing people.
Fate of migrants drew international concern and questions about Tunisia's policies.
Tunisian president ordered aid and transfer of migrants back to their countries.