Yemen troops, along with the US military, have driven out a few al-Qaeda members from their southern strongholds. The US has been backing military moves throughout the Middle East in places like Yemen for over a year. Many countries want to rid themselves of the issues involving the terrorist cells linked to al-Qaeda, which is why the capture of places like the town of Jaar and the city of Zinjibar is very important.
The US had a command center at an air base in the southern desert to help support local troops on their quest to get rid of the terrorist cells. It took many weeks for Yemen to finally win. The US military moved in to help because it considers some of the members in Yemen to be very dangerous, especially in launching attacks on the US.
Many of the more recent attacks involving US and local troops are in smaller towns and valleys around the mountains or deserts, where it is easier for the terrorists to hide. A few are in coastal towns. The US may be moving out of the region in terms of troop size, but they are also on hand and ready should they need to move back in. Some in the terrorist cells threatened to attack Sanaa, which is the capital of Yemen. They issued a statement that those working with the help of the US should be attacked. Yemen, it seems, did not want to wait for that to happen and decided to go in early in the morning to get the surprise drop on the rogue factions.