More than two years after 276 Chibok schoolgirls were abducted in Nigeria by Boko Haram, 219 are thought to remain in captivity. Or they did, until this week when two girls were recovered, raising hopes for the remaining group.

Until this point, despite ardent campaigning by family members and more further afield and bold claims from the government of eradicating the jihadist group, little progress had apparently been made.

On the two year anniversary in April, Boko Haram released a video purporting to show 15 of the abducted schoolgirls. It was the first possible sighting of the girls since a video in May 2014.

Now that two girls - Amina Ali Darsha Nkeki and Serah Luka - have been found, the question arises as to whether there is hope for the remaining 217 Chibok girls and the thousands of other abductees living under Boko Haram.

The issue is complex, the Nigeria Researcher for Christian Solidarity Worldwide told Christian Today.

"The Chibok girls are prized possessions for Boko Haram, because there has been such a huge campaign and publicity surrounding them" and so the group are unlikely to liberate the girls without some form of exchange.

President Muhammadu Buhari said "Amina's rescue gives us new hope and offers a unique opportunity to vital information." Meanwhile the governor of Borno State, where Chibok is located, said the army was drawing up plans and moving into a Boko Haram forest stronghold in a bid to rescue the remaining girls.

"We believe that in the coming weeks we shall recover the rest of the girls," Governor Kashim Shettima told reporters. "The military is already moving into the forest."

Nigerian authorities have faced overwhelming criticism for their failure to find the girls over the past two years. President Muhammadu Buhari, elected over former President Goodluck Jonathan last May, has pledged to fight Boko Haram's brutal insurgency and made security a key pillar of his campaign. However, despite the Chibok case being brought to international attention through the #bringbackourgirls campaign and a number of false rumours of their release, the girls have remained missing.

Boko Haram has been present in Northern Nigeria for almost seven years, seeking to impose its harsh interpretation of Islam on Africa's most populous nation.

Around 20,000 people have died and more than 2.5 million have been displaced as a result of the insurgency.

There have been increasing reports that Boko Haram forces are weakening, and the rescue of the 100 captives this week (a group of which one of the Chibok girls was part) appears to corroborate this.

On May 14, French President Francois Hollande told a security summit in Nigeria that "[Boko Haram] has been weakened, it's been pushed back, it's been chased around and has given up the territories it was controlling, and as a result it's being even better targeted and fought. However, this terrorist group remains a threat."

"It appears that Boko Haram are on retreat and are weakening, but given the fact that it is allied to it in so many countries, we can't count on it," CSW's Nigeria researcher told Christian Today.

"For example, in 2015 the leader released a very depressed video saying Boko Haram was defeated, and then another was released denying it, so there is clear they are shaky. It seems they are on the back foot," she said.

"The security situation in Northern Nigeria is very difficult, this makes it hard to get accurate information," Tania Corbett of Open Doors told Christian Today. "What we do know is that over the past few weeks Nigerian media have reported several times that people who have been kidnapped by Boko Haram have been found during security operations in Northern Nigeria," she said. "We hope and pray that Boko Haram are weakening as reports suggest but we do not know."

Media reports issued by the army suggest that Nigerian forces are making headway in clearing the Sambisa forest, and as pressure mounts, there is hope that more people will be released as the jihadists cannot hold territory.

The CSW researcher said that, according to local sources, the "husband" of the first girl discovered said that he had escaped Boko Haram with her and the child she bore because they feared starvation.

"Reportedly the army are beginning to block supply routes, and military operations are increasing in intensity, and so hunger and ill health are becoming issues for both hostages and Boko Haram fighters," they said.

The territory held by Boko Haram is seemingly decreasing, and with that comes a hope that more hostages will be released. This is in part due to the publicity garnered by the #BringBackOurGirls campaign, but that camapign is also the reason that the girls are likely to be the last released. It's thought six of the girls may have died, so the missing 217 may be reduced to 211.

"We are praying that more hostages will be released, including Chibok girls. Two already have been, and even that is a bit of a miracle," said the CSW researcher.

"We just need 211 more of those miracles."