Dozens of top intelligence and military officers have been assassinated in recent months in a savage campaign widely attributed to jihadists while complex attacks have been conducted against key military installations, all indicating Al Qaeda in the Arabian Peninsula is still a force with which to be reckoned.
The group, considered the most dangerous of Al Qaeda's affiliates from the badlands of northern Pakistan to Morocco , includes some of the network's most effective commanders, bomb-makers and ideologues.
Despite heavy losses, including several important leaders, from U.S. airstrikes in the last couple of years, AQAP remains a coherent force  that counterinsurgency analysts say is steadily regrouping.
In 2012, the Yemeni military, heavily supported by U.S. airstrikes and equipment, drove AQAP out of the jihadist emirate it had established in south Yemen's Abyan province by exploiting a seething separatist campaign in the region.
But now, the analysts say, AQAP has moved into the eastern province of Hadramaut, which covers a third of the impoverished country, to establish a new base of operations under veteran jihadist Nasir al-Wuhayshi, Osama bin Laden 's personal secretary in the 1990s.
Wuhayshi's importance in the global jihadist network was underlined in August 2013 when Al Qaeda leader Ayman al-Zawahiri , an Egyptian who took over when bin Laden was killed by U.S. Navy Seals in Pakistan May 2, 2011 , appointed him Al Qaeda's general manager.
While Wuhayshi was regrouping in Hadramaut, the bin Laden clan's ancestral home and a longtime AQAP bastion, he has also overseen stepped-up infiltration of Yemen's intelligence services and the army.
This is borne out by the wave of assassinations of senior officers , particularly from the intelligence agencies that spearhead the anti-jihadist operations of the military headed by President Abed Rabbo Mansour Hadi  who launched the U.S.-backed offensive that regained Abyan.
U.S. officials estimate as many as 100 Yemeni officials and tribal leaders have been slain  since mid-2012. In August 2013, analyst Daniel Green at the Washington Institute for Near East Policy put the toll at more than 90.
Among the victims:
-- Brig. Gen. Salim Ali Qatan, commander of the southern military region that includes Abyan, was killed June 18, 2012, by a suicide bomber disguised as a street beggar in the southern port city of Aden. He had led the military operations that drove AQAP out of Abyan.
-- Col. Abdullah al-Mushki, a high-ranking security chief, was shot to death by gunmen on a motorcycle, a tactic widely used by the assassins, in Dhammar province south of the capital Sanaa Jan. 17, 2013.
-- Col. Abdullah al-Rabaki, another senior military intelligence officer marked for assassination in leaflets circulated in the port of Mukalla in Hadramaut, was shot to death by motorcycle gunmen May 18.
-- Col. Abdulrahman Mohammed al-Shami, one of the top army intelligence chiefs in Sanaa, was gunned down by motorcycle-riding assassins Oct. 24 as he left his home.
There have been dozens more such killings across the country on the southwestern tip of the Arabian Peninsula.
These underline how Yemen's security services are seemingly powerless to stop the attacks because of the woeful lack of collaboration between the rival centers of power and their inability to penetrate the jihadist network.
Prime Minister Mohammed Salem Basindwa was targeted Sept 1 by gunmen who ambushed his motorcade in Sanaa as he drove home from his office.
He was not harmed, but the attack served to illustrate the reach of the assassins and the extent of their intelligence system.
The assassinations are taking place amid rising political tensions as Hadi battles to impose order in a country torn by jihadists, the southern separatists and northern Houthi rebels. There's also a bitter power struggle within the military between Hadi and the family of his discredited predecessor, Ali Abdullah Saleh .
The regime blames Al Qaeda for all the attacks. But U.S. analysts Casey L. Coombs and Hannah Poppy observe in a new study for the Combating Terrorism Center at West Point that other parties, including competing military groups, may have a hand in the assassinations as well.
"Ex-President Saleh and his longtime ally Gen. Ali Mohsen al-Ahmar, considered Yemen's two most powerful actors for decades, are the highest profile if not likeliest suspects," they noted.