Mohammed Yusuf NAIROBI, KENYA? Saudi-led coalition airstrikes against Houthi Shirsquo;ite rebels in Yemen began last week, but already, security experts are warning that the conflict in Yemen might cause a new security challenge to East Africa. Saudi Arabia is leading an Arab coalition with aerial bombardments to stop the advance of Shi#39;ite Houthi rebels on the port city of Aden and assure the internationally recognized government led by President Abd-Rabbu Mansour Hadi returns to power. Click to enlarge x Click to enlarge Currently 10 primarily Sunni-Arab states - including several Gulf states, Sudan, Egypt and Morocco - are taking part in the Saudi-led coalition in...