Since the beginning of 2012, roughly 60 officials have been killed throughout Yemen. Nearly all the officials worked in the country's military, security or — most often — intelligence sectors. Except for occasional assaults in the capital, most of the assassinations have occurred in the southern port city of Aden or its surrounding provinces. The assassins have used a variety of methods — primarily suicide attacks, sticky bombings and assaults by gunmen.

In contrast, the recent Sanaa assassinations have been nearly identical in style and have primarily targeted officials specifically involved in counterterrorism activities. Since Aug. 30, armed assailants have killed six Yemeni security officials in Sanaa — a mix of low- to high-ranking officers, including high-value targets such as a foreign security national investigator working for the U.S. Embassy. The most recent killing in the capital occurred early Oct. 16, when an unidentified gunman on a motorcycle reportedly shot Gen. Khaled al-Hashim, an Iraqi who had reportedly been working with the Yemeni government. So far, none of the assailants have been apprehended. 

The Sanaa attacks share several unique hallmarks. Most of the assailants attacked on motorcycles, which allow attackers to maneuver effectively when tracking and approaching targets and then to flee quickly. The consistent use of firearms rather than, say, improvised explosive devices, is also notable. This tactic can be highly effective when employed by well-trained individuals and in the close-range scenarios reportedly common among the Sanaa attacks. The consistency of the tactics employed and the similarities among the officials targeted strongly suggest that a coordinated group of militants have carried out the attacks.

Still, the identity of the attackers remains unclear. Militants associated with al Qaeda in the Arabian Peninsula could be to blame since many of the security and intelligence officers killed had been involved in operations against the group. Moreover, unmanned aerial vehicle strikes targeting the al Qaeda franchise in Yemen have increased significantly — the 36 airstrikes conducted in 2012 are more than the past four years combined — making retaliation a plausible motive. Indeed, after the government launched a major offensive against the al Qaeda node in June 2012 and continued to attack al Qaeda cells in the south, the group conducted a series of reprisal assaults, including a suicide attack against a police academy in Sanaa on July 11. Tribal Yemenis with family members who were mistakenly targeted or affected by recent airstrikes would also have motivation to seek vengeance.

However, non-jihadist elements could also be responsible. Yemeni President Abd Rabboh Mansour Hadi has been attempting to restructure the country's armed forces in order to consolidate power and undermine factions loyal to former President Ali Abdullah Saleh. Pro-Saleh elements angry about the former president's departure or the military restructuring could well be seeking retribution. Saleh loyalists have responded violently to losses of power in the past. For example, an attack in August by the pro-Saleh Republican Guards on the Yemeni Ministry of Defense was reportedly carried out in response to the military reorganization. More recently, the U.S. Embassy investigator assassinated Oct. 11 was purportedly a member of a team working on the restructuring.

Regardless of who is responsible, attacks on security officers in Sanaa will likely continue. Unless Hadi can consolidate power and balance Yemen's various political factions — he has been attempting to do so unsuccessfully since he unofficially took power in November 2011 — the internal government and security forces cannot stabilize Sanaa to the degree necessary to secure the city and suppress the militant threat.