Washington - Boko Haram is flush with cash and weapons after a string of battlefield advances, but the militants could face a tougher fight with the country's neighbors, US intelligence officials said Friday.
The group is "financially secure" from bank robberies, kidnappings and other sources, and is able to go "toe-to-toe" with the military after capturing an arsenal of arms, the intelligence officials told reporters.
However, the group could soon face an unprecedented test on the battlefield against more capable forces from Cameroon, Chad and Niger.
The military intervention of neighboring powers "potentially can be a game changer in a positive way," one intelligence official said.
The comments came as Boko Haram suffered heavy losses after launching a major attack into Niger on Friday for the first time.
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The clashes involved troops from Niger as well as Chad, which has adopted a leading role in the fight against the Islamists.
US officials drew a possible parallel with Somalia, where regional armies have rolled back Shebab extremists, and said Boko Haram might find its power curtailed by neighboring states.
Inside the country, Boko Haram has been steadily gaining in strength, seizing 30 towns and villages in the space of a year, officials said.
The advance has allowed the group to carve out a safe haven, from which it has staged more sophisticated operations and attacks over a wider area.
Boko Haram, with about 4,000-6,000 fighters, also has seized armored personnel carriers from retreating troops, allowing the group to "up its game" on the battlefield, one intelligence official said.
The armored vehicles have enabled the militants to advance on towns and villages more rapidly as a result, said the official, speaking on condition of anonymity.'Affinity' for IS'
The group's brutality and "sense of vengeance" is heavily shaped by its leader, Abubakar Shekau, officials said.
And there is no clear heir apparent if Shekau is killed in battle.
As Boko Haram pushes out of the northeast, it will pose a growing threat to Westerners based in Nigeria.
But there are no signs the group has the ability to stage attacks on oil fields in the country's south or to orchestrate terror attacks in the West.
In propaganda videos, Boko Haram has expressed "an affinity for ISIL (the Islamic State group)" but "there are still a lot of questions out there as to how ISIL views Boko Haram," an official said.
"The Arab world is still incredibly racist" and jihadis in the Middle East are unlikely to view militants in Nigeria as fellow warriors with an equal status, the official added.
Boko Haram is suspected of likely still holding 276 schoolgirls kidnapped from the town of Chibok last April.
The missing girls grabbed headlines and sparked a social media campaign last year but their plight has faded from headlines.
"As far as we know, the group's still holding the girls," the official said.
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Kidnapping "has been a habit of Boko Haram" for years and "this isn't anything new," the official added.
The April kidnapping of the schoolgirls "got notoriety because of the size" of the group abducted, the official said, speculating that the girls are likely dispersed among the militants and not held in one place.
The military, meanwhile, has struggled to adapt to the threat posed by Boko Haram.
The army has fallen into a downward spiral, with heavy casualties damaging morale, which in turn has prompted desertions, officials said.
The US Defense Intelligence Agency's director, Lieutenant General Vincent Stewart, told lawmakers in written testimony this week that Nigeria's army has "been challenged by mass desertions, as troops often retreat upon their first contact" with Boko Haram.
But the group's "strengths could be its weaknesses" as the more ground it controls, the more vulnerable it will become to conventional military attacks as tries to defend large stretches of territory, the official said.
Boko Haram's campaign of terror could also backfire in other ways.
The group could eventually face a food shortage as it has driven out whole populations in areas under its control, leaving farms abandoned with no one to plant and harvest crops.