The Saudi-led coalition air crafts shelled early Friday several air defense sites under Houthi control in the Taiz governorate south of Yemen, Sky News reported. Meanwhile, the Houthis moved their forces and reinforcement from Al Mukha district east of Taiz to Aden city which has been the scene of fierce fighting amid attempts by the rebels to seize the key governorate stronghold. Security sources said that the Arab coalition warplanes also hit Houthi fighters near the Bab-el-Mandeb international strait, as well as Mayyun Island off the southwest coast of Yemen. On the other hand, the Houthis managed to advance in Aden with the help of ex-military troops loyal to former president Ali Abdullah Salah. Yemeni eyewitnesses said Thursday that foreign troops had landed in the Yemeni port city of Aden. The Saudi ambassador to Yemen asserted that there were no Saudi ground forces in Yemen, noting that this option is still subject of discussion.