Unidentified gunmen shot dead an army colonel in his car in Yemen's southern port city of Aden late on Friday and two soldiers were injured when a car bomb exploded in another major southern port on Saturday, security sources said.
The attacks follow dozens of others directed at security targets in the US ally in recent months, killing hundreds, and come as the army is conducting a big operation against Islamist militants in the southern provinces of Shabwa and Abyan.
Western countries fear further destabilization in Yemen could give more space to al-Qaida in the Arabian Peninsula (AQAP), the local branch of the global Islamist militant movement, to plot attacks on international targets.
AQAP and its local ally, Ansar al-Sharia, have been waging an insurgency in southern Yemen for more than three years, battling both government forces and local tribal militias.
Colonel Sanad Badr was shot dead in his car by unknown assailants on a major Aden street late on Friday, a local official said.