Rebels in Yemen seized one of the government's last strongholds in the country Thursday, leading diplomatic and military experts to speculate about how fighting may evolve on the oil-rich Arabian Peninsula.
Houthi rebels took central parts of the southern city of Aden, including the presidential palace, overnight. Meanwhile, officials said al-Qaeda militants in the country had freed about 300 inmates in the city of al-Mukalla, which experts say could boost the clout of extremist groups in the region.
A coalition of states led by Saudi Arabia has continued to pound rebel strongholds from the air as Yemen slips further into chaos, prompting worries that a more forceful intervention could become necessary. Yemen forms most of the southern border of Saudi Arabia, a top energy producer which holds about 17 percent of the world's proven oil reserves.
"If I were advising the Saudis, (I'd say) an air war is not going to do it for you, and a full ground invasion from the north is a very bad idea," said Nabeel Khoury, a non-resident senior fellow at the Atlantic Council, and the State Department's deputy chief of mission in Yemen in 2004-07. "You can insert a small force of elite soldiers, and put them in the south where they can intercept the Houthis if they further advance."