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Suspected Al Qaeda suicide bombers disguised in military uniforms stormed into an army base in southern Yemen on Friday, killing 14 soldiers and wounding more than 20, Yemeni officials said.

The dawn assault on the coastal base in Abyan province involved four suicide bombers in an army pick-up truck laden with explosives and a gunbattle with soldiers who were caught sleeping.

The attack highlights the increasingly brazen tactics used by militants in this impoverished Arab Peninsula country and the many challenges Yemen's new leadership faces as it struggles, with U.S. help, to route militants and bring security to the nation.

Washington considers Al Qaeda in the Arabian Peninsula, as the Yemeni branch of the network is known, to be the group's most dangerous offshoot, and holds it responsible for several failed attacks on U.S. territory.

The Abyan attack came a day after suspected U.S. drone strikes killed at least seven Al Qaeda-linked militants in the same area in the south. It also followed a recent visit to Abyan by Yemen's Defense Minister Gen. Mohammed Nasser Ahmed, which was meant to showcase the military's strength in a province where the group last year controlled entire cities and towns.

In June, Yemeni troops backed by U.S. airpower and advisers drove Al Qaeda militants out of southern cities and into mountain refuges. Earlier, the militants had seized large swaths of territory in Abyan during a security vacuum left by last year's uprising against the country's longtime authoritarian leader, Ali Abdullah Saleh. They also seized thousands of firearms, as well as tanks and armored vehicles in raids on arms depots and barracks.

Military officials said Friday's attack started when four bombers, dressed in military uniforms, drove the pickup to the base and opened fire on its guards, killing two.

Three of the attackers then jumped out of the pickup and started shooting at soldiers who had rushed out, awakened by the gunfire, the officials said. The fourth bomber rammed the explosives-laden vehicle into a group of soldiers and blew it up. The other three attackers were killed as their suicide vests detonated during the shootout with the soldiers.

The officials said the attackers apparently wanted to assassinate the base commander but never got close to his quarters. The head of the military police on the base was among those killed in the attack, said the officials, speaking on condition of anonymity in line with military regulations.

Yemeni security officials, meanwhile, said they believe militants have a hit list of officials on the new government that came to power earlier this year. They expressed fears that Al Qaeda has also infiltrated military ranks and has informants who report on military movements. The security officials spoke on condition of anonymity because they were not authorized to talk to the media.

Saleh, Yemen's former president, was toppled in the country's uprising -- the fourth longtime Arab ruler to fall as a result of the Arab Spring. But constant friction between Saleh's remaining supporters and those of his former deputy who is now president, Abed Rabbo Mansour Hadi, have added to the volatile mix.

Since Hadi's government offensive drove Al Qaeda from southern towns and cities, militants have sought refuge in mountain areas and have retaliated with assassinations of top security officials. They have also staged deadly suicide bombings targeting the military and civilian militias working alongside the army.

One of the worst attacks against the Yemeni army took place on May 21, when a suicide bomber -- who turned out to be a son of a colonel -- blew himself up in the middle of a military rehearsal in the capital, Sanaa, killing around 100 soldiers.

A month later, an Al Qaeda suicide bomber detonated his explosives among a crowd of Yemeni police cadets, killing at least 10.

In March, Al Qaeda militants launched a surprise pre-dawn attack on a southern base while troops slept, killing 185 troops and capturing 73. The fighters sprayed tents where soldiers had been sleeping with gunfire. They dumped their bodies in the desert, some beheaded, and paraded dozens of captured soldiers through a nearby town.