Jihadists from the al-Qaeda affiliate al-Shabab have reportedly executed six Christians in a Kenyan town that borders Somalia, marking the latest in a wave of attacks targeting Christians in the predominantly Muslim region.

The attack was aimed at “forcing” Christians out of northeastern Kenya’s Mandera town region, reports BBC, citing a radio station run by the Somalia-based al-Shabab group.

A spokesman for the jihadist group told the British outlet that al-Shabab “wanted non-Muslims to leave what it regarded as Muslim areas.”

The terrorists also attacked a telecommunication site to divert the attention of the Kenyan security forces from the “actual attack,” said Mandera County commissioner Fredrick Shiswa.

“This must have been planned over a long period… It was executed with a lot efficiency,” Shiswa told BBC.

The British news agency learned from local police that the “the grenade and gun attack was launched on a residential block in Mandera town when people were sleeping.”

Mandera lies along Kenya’s border with Somalia, making the region vulnerable to attacks from al-Shabab.

BBC notes:

The militants usually cross the porous border, carrying out deadly attacks on civilians and security agents before fleeing back.

In 2015, Kenya’s government announced that it would build a security wall along parts of the border to keep the militants out. But it is likely to abandon the plan because of strong resistance from Somalia’s government and border communities.

In recent years, al-Shabab has been targeting Christians in Somalia and Kenya in an effort to push them out of areas they consider to be Muslim-only regions.

BBC acknowledges:

In December 2014, al-Shabab killed 38 non-Muslims at a quarry after separating them from Muslim workers. A few months earlier, 28 people were killed after Muslim passengers were split up from the other passengers.

The Kenyan government has reportedly been recruiting Muslims to become police officers, a strategy that has had some success in reducing attacks by al-Shabab.

Near the Somali border in northeastern Kenya, Muslims “increasingly see al-Shabab as a threat to their own interests, and are making a concerted effort to improve relations with Christians living there,” reports BBC.

“Many of the Christians are skilled workers from other parts of Kenya, making a vital contribution to hospitals and schools,” it adds. “The north-east is one of Kenya’s poorest areas and if they are driven out public services will worsen.”

In 2014, al-Shabab was responsible for the third-most terrorist attacks in the world. The U.S. military has carried several airstrikes against the group this year.

Pressure from the Kenyan military, backed by its Somali counterpart, has been pushing al-Shabab militants into Kenya from Somalia. The Kenyan military is part of the African Union mission combating the group in Somalia.

In October 2011, Kenyan troops entered Somalia to combat the jihadist group. Earlier this year, Kenya decided to shut down the Dadaab refugee camp, considered to be the world’s largest, because it had become a recruitment center of al-Shabab.

Kenya has accused the terrorist group of using the camp as a base to launch attacks on Kenyan soil.