The Houthis' threats to attack shipping lanes and the fresh deployment of IRGC experts to the Red Sea coast have raised concern in Yemen.
It is possible that al-Qaeda has so far failed to make contact with al-Zawahiri's most likely successor, Egyptian extremist Saif al-Adel, analysts say.
Even as reconstruction moves slowly and economic conditions are still dire, residents of Iraq's once thriving cultural centre of Mosul hail the improved security situation.
Left without a sanctuary or charismatic leader, ISIS has lost much of its credibility and power, and is scrambling to remain relevant, analysts say.
ISIS leader Abu Hasan al-Hashimi al-Qurashi was killed during an October operation, following in the footsteps of his short-lived predecessors. Details of his demise have started trickling in.
Life has been hazardous for children in Houthi-controlled areas, who face injury or death from mines or snipers and recruitment as soldiers.
There has been heightened tension in Daraa province after it came to light that a number of local groups have pledged allegiance to ISIS.
A dozen bodies of civilians and soldiers were found in a mass grave near Palmyra's archaeological theatre. In 2016, ISIS executed at least 280 people in the city.
The restoration project aims to turn the tables on ISIS, transforming the damaged monument into an educational centre on Ninawa's history.
Al-Qaeda has been using explosives in Shabwa and Abyan that are much like the ones made with Iranian expertise in Houthi-controlled areas.