On December 17th, American cruise missiles, launched from warships offshore, struck two al Qaeda terrorist training camps in Yemen. One target was in the south, the other in the north. The missile attacks were done in cooperation with Yemeni security forces, which moved in right after the missiles hit, to take prisoners and seize equipment and documents. The Yemeni troops found 34 terrorists killed, and captured 17 others. Normally, the Yemenis leave al Qaeda alone, in return for assurances that there will be no more attacks in Yemen. But this operation was carried out because the government believed that the terrorists were planning multiple attacks inside Yemen. At least one other attack was made on an al Qaeda base, using only Yemeni security forces.
Al Qaeda is able to make sanctuary deals in Yemen because the government has to deal with pro-al Qaeda Yemeni groups, including powerful political parties. There are still many Yemenis who have a grudge against the government. Most of this can be traced back to the civil war that ended, sort of, in 1994. That war was caused by the fact that, when the British left Yemen in 1967, their former colony in Aden became one of two countries called Yemen. The two parts of Yemen finally united in 1990, but a civil war in 1994 was needed to seal the deal. That fix didn't really take, and the north and south are pulling apart again.
Meanwhile, Saudi Arabia has joined the government in fighting Shia tribal rebels fighting near the Yemen-Saudi border. The Saudis believe that al Qaeda members will try to sneak back into the kingdom, rather than risk capture by Yemeni troops. The Saudis fear that the rebels are harboring a number of Saudi al Qaeda members, and that these terrorists were behind an August 28 attempt to assassinate a senior Saudi official. That attempt involved a bomber who hid the bomb in his ass. You can't get much explosives up there, and the attempt failed. But if it were tried in an aircraft, the results might be catastrophic.
The fighting in the north has been going on for five months. The government has turned to the United States, as well as Saudi Arabia and other Gulf Arab states, for assistance. These Arab nations have sent over a billion dollars in cash, and the Saudis are contributing troops, warplanes and money, The U.S. has been operating more UAV sorties over Yemen, and some American Special Forces troops have arrived in Yemen to help local security forces in their operations against the Shia rebels and al Qaeda.