Nigerian soldiers have fought off a series Boko Haram attacks over the weekend, the army and military sources said on Monday, January 21.

On Saturday, troops “inflicted devastating man and equipment casualties” on the group in the Baga area of Borno state, on the shores of Lake Chad, the army said in a Sunday statement.

The insurgents used a suicide car bomb (SVBIED) and two “gun trucks” in an attempt to break into a defensive position, Colonel Onyema Nwachukwu said.

Five militants were “neutralized” in a counterattack by army, navy and air force special forces troops, “including a driver and a gunner firing from a gun truck, a suicide bomber in a vehicle loaded with IED and two other terrorists,” Nwachukwu said, adding that the SVBIED and one technical were destroyed, and one anti-aircraft gun and three AK-type rifles were recovered.

On Sunday, troops “successfully defeated Boko Haram terrorists” who attacked a military base in Buni Yadi in Yobe state, northeast Nigeria, the army tweeted.

The attack began around 4:15 p.m. and fighting continued for two and a half hours, Major Nureni Alimi said in a Monday statement, adding that “some of them were neutralised” and others fled, some with gunshot injuries.

Four soldiers sustained minor injuries, Alimi said.

Two “gun trucks” along with anti-aircraft ammunition and rocket-propelled grenades were recovered.

Two military sources said the Islamic State West Africa province faction of Boko Haram was behind the weekend attacks in Baga, Kareto and Buni Yadi.

The sources both said four soldiers were killed as they repelled the attack in Buni Yadi during “intense” fighting that involved air strikes.

Islamic State in a statement claimed ISWA fighters attacked Kareto on Saturday, and its Amaq propaganda agency said ISWA fighters had attacked both Baga and Kareto.

Meanwhile, two Boko Haram fighters were also killed in operations in the Mafa district of Borno on Saturday, the army said in a Sunday statement.

The fighters who had “infiltrated” Kajeri Maye village were killed in a clearance operation and two female hostages were freed, Nwachukwu said.

Troops recovered various arms and ammunition including 36 hand grenades, Nwachukwu said, adding that clearance operations were continuing in the area.

It is unclear which faction of Boko Haram was responsible for that attack.

Boko Haram split into two factions in mid-2016. One is led by Abu Mus’ab Al-Barnawi and largely focuses on attacking military and government targets, while the other, led by Abubakar Shekau, is notorious for suicide bombings and indiscriminate killings of civilians.

Shekau has pledged allegiance to ISIS leader Abu Bakr Al-Baghdadi, but ISIS central gave its formal backing to the Barnawi faction, which is known as Islamic State West Africa province.

Last week, six soldiers were killed and 14 injured in a Boko Haram attack on Kamuya village near the home of Chief of Army Staff Lieutenant General Tukur Yusuf Buratai’s mother.

Nigeria’s President Muhammadu Buhari said in December 2015 that Boko Haram was “technically defeated” after a sustained counter-insurgency.

But on January 9 he acknowledged setbacks in the fight-back, including “battle fatigue” among soldiers from a wave of guerrilla style hit-and-run tactics and suicide bombings.

Buhari was elected in 2015 on a promise to end the conflict and security has again become an election issue as he seeks a second term in the presidential election on February 16. National Assembly elections will be held the same day, while regional polls are set for March 2.

More than 27,000 people have been killed since the insurgency began in 2009, and 1.8 million people are still homeless and in need of humanitarian assistance.

Nigerian troops returned to Baga on January 9 after a wave of ISWA attacks against military bases in late December that forced more than 30,000 civilians to flee.

Last week, around 10,000 people already displaced by the conflict were forced to flee after an attack on Rann, a remote village near the border with Cameroon. That attack was claimed by the Shekau faction of Boko Haram.

The movement has increased pressure on aid agencies providing humanitarian assistance. It has also raised questions about how elections can be held in areas hit by fighting.

With reporting from AFP. this post was updated on January 21 with additional information on the Buni Yadi attack.