The situation in Yemen is becoming increasingly complicated with the country divided between two centres of power that don’t recognise each other. <br /><br />Sunni tribes have mobilised their forces to expel Shia Houthi fighters from their provinces. <br /><br />Al Jazeera's Mohamed Vall reports from Aden.<br /><br />More on our website: http://aljazeera.com<br />Follow us on Twitter: http://twitter.com/AJEngligh<br />Subscribe to our channel: http://bit.ly/AJSubscribe <br />Find us on Facebook: http://facebook.com/aljazeera
