(http://news.bbcimg.co.uk/media/images/75306000/jpg/_75306515_line976.jpg) Analysis: Thomas Fessy, BBC West Africa correspondent Cameroon, Niger, and now Chad.
Boko Haram has been attacking Cameroon for nearly a year, but now it has carried out attacks in both Niger and Chad within a week, making those countries pay for their participation in a regional offensive against the Nigerian insurgency.
But can the Islamist militants fight on four fronts at the same time?
Clearly, Boko Haram wants to show that it can strike wherever it wants. But its attacks have all so far been launched from Nigeria - it has yet to gain local endorsement in neighbouring countries, which it will need in order to transform what has become a regional war into a regional insurgency.
Desperate escape across Lake Chad (http://m.bbc.co.uk/news/world-africa-30900915)
(http://news.bbcimg.co.uk/media/images/75306000/jpg/_75306515_line976.jpg) Approximately 7,000 people fled to Ngouboua after Boko Haram attacked the Nigerian border town of Baga in January.
Boko Haram leader Abubakar Shekau denounced the president of Chad, Idriss Deby, in a video released shortly after the coalition was formed and declared "war" on Chad.
The militants have also continued their insurgency in north-eastern Nigeria - at least 21 people were killed on Thursday in two separate attacks in Borno State, witnesses told AFP.
Militants killed 12 people in the village of Akida and nine in the village of Mbuta, community leader Mustapha Abbagini said.
(http://news.bbcimg.co.uk/media/images/75306000/jpg/_75306515_line976.jpg) Boko Haram at a glance
(http://news.bbcimg.co.uk/media/images/80142000/jpg/_80142357_afp_bh.jpg)
- Founded in 2002, initially focused on opposing Western education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched military operations in 2009 to create Islamic state
- Thousands killed, mostly in north-eastern Nigeria - also attacked police and UN headquarters in capital, Abuja
- Abducted hundreds, including at least 200 schoolgirls
- Controls several north-eastern towns
- Launched attacks against neighbouring Niger and Cameroon in 2015
Cameroon punished (http://www.theinfostride.com/news/world-africa-30880979)
Why is Boko Haram so strong? (http://www.theinfostride.com/news/world-africa-30933860)
(http://news.bbcimg.co.uk/media/images/75306000/jpg/_75306515_line976.jpg) Approximately 3.2 million people in Nigeria have fled their homes as a result of the Islamist insurgency, officials say, with many living in makeshift camps.
Nigeria launched an investigation (http://m.bbc.co.uk/news/world-africa-31386340) on Tuesday after reports of rapes, child trafficking and other abuses in the camps.
The conflict with Boko Haram has forced a postponement of Nigeria's presidential and parliamentary elections from 14 February to 28 March.
Source: BBC