The three states are former colonies of France and are all ruled by military juntas following coups — the most recent of which took place in Niger, where soldiers in July ousted President Mohamed Bazoum.
Mali's junta leader Assimi Goita on Saturday announced the signing of a charter establishing the so-called Alliance of Sahel States (AES) which he said would "establish an architecture of collective defense and mutual assistance."
Burkina Faso's interim president Ibrahim Traore and Niger's de facto leader Abdourahmane Tchiani were also present at the signing of the charter, which states that its objective is to create "an architecture of collective defence and mutual support between the contracting parties."
What does the AES mean for the G5 Sahel?
Mali's foreign affairs minister, Abdoulaye Diop, told reporters that the AES alliance "will be a combination of military and economic efforts between the three countries. And priority will be given to the fight against terrorism in all three countries."
Seidick Abba, a journalist who reports on the Sahel region, told DW that the new alliance "almost definitely" spells the death of the G5 Sahel group.
Mutaru Mumuni Muktar, executive director of the West Africa Center for Counter Extremism, agreed — stressing that the breakaway by Mali, Burkina Faso and Niger was long expected.
"In all the three countries there's a strong anti-French sentiment and this has been building on over time," he told DW.
"And at the moment we are seeing significant, actions that are taken to get the G5 forces out [or] sidelined and also French operations and French efforts out of the space."
Muktar doesn't see how much G5 Sahel forces would be able to do under these circumstances.
"And eventually we are going to see that being off the table in terms of dealing with the threats in these spaces," Muktar said.
Chad and Mauritania — the other two members of the G5 Sahel — were left out of the new alliance signed in Mali's capital Bamako.
Sahel region ravaged by jihadism
Some 4.9 million people have been displaced as a result of the crisis. Insecurity in the Liptako-Gourma region — where the Malian, Burkinabe and Nigerien borders meet — continues to grow, according to the United Nations.
The UN stressed the urgent need to strengthen support and advance the fight against terrorism in the region.
Bram Posthumus, an expert on Africa's Sahel region, told DW that since soldiers took over in Mali, Burkina Faso and Niger, the security situation in those countries has worsened.
"I mean, if anything, I think the security situation has deteriorated in every single one of the three Sahel nations. If we want to limit ourselves to Mali, Burkina Faso and Niger," Posthumus said.
"Coups do not usher in an era of stability. They usher in eras of instability. And they have given the adversaries, the non-state armed groups, the opportunity to increase their influence and their writ and the areas they control. So no improvement of security in the Sahel after the coups. The contrary has happened. A deterioration of the security situation."
But the junta-led countries believe they have the solutions to the crisis and want to chart a new path.
Seidick Abba however doubts how useful isolating Chad and Mauritania would be for the other three.
"For example, it is in Niger's interest to have a common counter-terrorism strategy with the [Chad], since Niger also faces the challenge of Boko Haram," Abba said.
The AES lacks capacity and funding
Muktar said the three nations also lacked the capacity and infrastructure needed to increase the security in the Sahel region.
"[Since] these military leaders took charge, there's [not] enough capacity to deal with the problem of violent extremism and the problem of insecurity and other security challenges that face the region," he said.
"They do not have enough funding. They do not have a sustainable economic model to to be able to deal with it sustainably. They do not have enough goodwill from the local population and other actors locally to be able to deal with that. And so I don't see how far this would go in terms of their capacity to sustain the relationship in dealing with violent extremism."
But the new alliance is also seeking to protect the coup leaders and solidify their position amid threats from the regional bloc ECOWAS to invade, for example Niger, if civilian rule is not restored.
Under the charter, the parties pledge to fight terrorism and organized crime, it says.
"Any violation of the sovereignty and territorial integrity of one or more Contracting Parties shall be considered as aggression against the other Contracting Parties and shall oblige all Contracting Parties to provide assistance and redress ... including the use of armed force," the charter states.
Opportunity knocks for Russia
Muktar believes the three countries aren't looking for collaborations from the West in this latest move — a posture he said would perhaps present new opportunities for Russia.
"I think that significantly they are not looking to Western partners for support. If anything falls directly in line with what Russia would like to see in space in this space, [then] that alliance can inure to the benefit of Russia's expansionist influence in West Africa," he said.
The Russian Wagner mercenary group already operates in the region, helping to provide security support.
"It expands the window of opportunity for Russia to amplify their presence and legitimize their presence in this space," Muktar said.
"Already we have we have Wagner forces that have been here for some years now, and that this particular alliance is directly, you know, in favor of Russia in this space."
Edited by: Keith Walker
While you're here: Every weekday, we host AfricaLink, a podcast packed with news, politics, culture and more. You can listen and follow AfricaLink wherever you get your podcasts.