Mohammed bin Salman, the crown prince of Saudi Arabia, will be visiting Washington next week to discuss defence cooperation. The kingdom is currently the biggest importer of US arms and is expanding its military procurement.

His trip comes as the Saudi-led coalition campaign against Houthi fighters in Yemen enters its third year.

A Houthi military spokesman told Al Jazeera that their snipers kill between six to eight Saudi soldiers and mercenaries every day, in addition to the destruction of at least three Saudi military vehicles daily. Houthi losses have also been great.

Al Jazeera's Hannah Hoexter reports on the battleground on the Saudi-Yemeni border.