article_snippet: The Houthis were on the verge of overrunning Aden, a strategic port that overlooks straits through which 20,000 merchant ships pass every year.
article_snippet: According to the U.S. Energy Information Agency, 3.8 million barrels of oil a day passed through the Bab el Mandab Straits in 2013.
article_snippet: Since then many army units have moved on the Red Sea port of Hodeida and surged south toward Aden.