GABORONE, Botswana — The Kenya Defence Force (KDF) says it has constructed the first 3 kilometers of a security fence along the north-eastern border with Somalia, which is aimed at preventing the infiltration of al-Shabab militants who have staged several mass-casualty attacks inside Kenya in the past four years.

According to Kenyan Interior Cabinet Secretary Joseph Nkaissery, the border wall will cover the entire 700-kilometer border with Somalia, which runs through the northeastern county of Mandera to the Indian Ocean coast.

Initially planned as a concrete barrier fitted with surveillance equipment and observation posts in 2015, the project has since been changed to a security fence of concrete poles linked through barbed wire and secured by electric fence and razor wire.

Tighter security fencing that would include the use of mesh wire is planned for nearly 200 kilometers of border sections defined as "security-sensitive."

Kenya embarked on the border wall project to prevent the infiltration of members of the Somali-based al-Shabab militant group, who have previously crossed the porous common border into Kenya to stage attacks such as bombings, shootings and grenade attacks in public places.

Al-Shabab started targeting Kenya for revenge attacks following its decision late in 2011 to deploy the KDF as part of the fledgling African Union (AU) force which is fighting the group in Somalia.

Speaking to journalists during a recent media tour of the newly completed section of the fence, KDF Engineering Department commander Major-General Thomas Cheptuko said the Army would seal up 30 kilometers of the porous land border within the next four months.

"We will do the first 30 kilometers within the stipulated time since people are energized. We are working closely with the Somalia National Army (SNA) to ensure that the construction work is done peacefully. The only possible challenge could be from Bula Hawa (clan), but SNA are working with us to ensure that the project progresses swiftly," Cheptuko said.

The Bula Hawa are a Somali clan which lives on the border with Kenya. It has repeatedly been accused of supporting the al-Shabab insurgency and allowing or helping Kenyan-bound terror units transit through its territory.

Despite combined Somali-Kenyan efforts to persuade the cross-border clan to embrace the border fence, the Bula Hawa remain bitterly opposed to the construction of the security fence and have threatened to stage disruptive attacks.

Mandera County Governor Ali Roba said the army would expedite the sealing up of the 30-kilometer-long stretch between the Kenyan town of Mandera and Bulahawa in Somalia because the majority of militants who have staged attacks were found to have entered Kenya through the same strip.

He said due to its proximity to the Bula Hawa clan across the border, the town of Mandera was more vulnerable to cross-border terror attacks.

"Our request was to re-energize and expedite the work for the first 30 kilometers in order to secure Mandera (town), and there is hope that we will succeed. We are happy with the progress of the public security sensitization program as visible work has been done, unlike in the last two months when we visited the site. We want our brothers from Somalia to do business with us, but only through the customs border so that we can be able to keep out the unwanted elements," Roba said.

The KDF took over the implementation of the project three months ago following a series of work stoppages blamed on pay disputes between the government and members of the National Youth Service (NYS), who were initially contracted to do the job.

Somalia initially opposed the border fence and threatened to take legal action citing possible infringements on its sovereignty. However, Mogadishu has since warmed up to the project and provided troops to secure the KDF construction teams against possible terrorist attacks from the Somali side of the border.