As the government's control in remote areas is weakened by the year-long unrest, constant conflicts in Yemen become one of the biggest challenges the transitional government faces in the impoverished country.
Since al-Qaida wings in Yemen and Saudi Arabia merged into Al-Qaida in the Arabian Peninsula (AQAP) in 2009, Yemen has been seen as a terrorist hotbed. In response, the country has been collaborating with the international community in its fight against militants.
The unrest, which started in early 2011, deepened the government's inability to battle the insurgents; as a result, extremist groups including AQAP and the Sharia supporters have been taking this advantage to expand their presence.
Besides AQAP, researchers said there are other militant groups in Yemen of different goals and strategies.
Muhammad Saif Haider, a researcher, said while AQAP operates covertly with a focus on foreign targets inside and outside Yemen, the Sharia supporters have mainly focused on occupying towns and staging wars against authorities.
AQAP, described as the most dangerous branch of the global terrorism network, has been responsible for almost all recent local and foreign covert plots.
Meanwhile, the Yemeni authorities, backed by the United States, are continuing its battles against militants who occupying Zinjibar, the capital of the southern province of Abyan.
According to some researchers, the number of militants in the country rose from 500 to around 3,000 people.
The reasons for this increase are the extremist groups' infiltration into tribes and security systems, soaring rates of unemployment, as well as the government's inability to control remote areas.
Ahmed Saif, executive director of Sheba Center for Strategic Studies, said there are many factors behind the momentum of militants in Yemen including the political situation, the country' s geography, the security factor and insufficient awareness.
"Also, if we look at the locations of militants we will discover they are based in oil trade routes in Shabwa and Hadramout," Saif said.
The stable financial situation is one of the most important factors which help militants grow and boost their strength, according to Saif, adding that "militant groups have recently started to rely on smuggling besides charity support."
Since a new government was sworn in and vowed to continue the war against terror and pursue militants until their last hide-out, militants have escalated their attacks.
According to researchers, there are other factors behind the momentum of the extremist groups in the country including the continuous exodus of Africans into Yemen and disorders inside the military and security systems.
The Interior Ministry has said hundreds from the Somali Shabab Group, an extremist group, infiltrated the country to back Yemeni militants.
Haider also said recent attacks revealed how the Saudi wing within AQAP remains the most important player as the researcher talked about the connection between escalating militant attacks and the efforts to restructure the armed and security forces.
"Statements by militants have pointed to the restructuring of the armed and security forces and this means the escalating attacks is connected to the issue," Haider said.
According to a power transfer deal brokered by the Gulf Cooperation Council and backed by the West, the Yemeni government will reform the army and security forces.
"In general, what is happening in Abyan and al-Bayda is part of the political and social landscapes in the country," he said.
"Al-Qaida has been expanding here for years and now it is taking advantage of the power transition," he said.
Abdul Salam Muhammad, head of a strategic studies center, said al-Qaida by itself is not that dangerous but logistic support it receives enables it to pose quite a threat.
In this regard, Nabil al-Bukairy, a researcher, said some people from the former regime are still controlling the army and security forces and are attempting to launch a counterrevolution after the mass protests.
