The military campaign by Nigeria and neighbouring nations to combat the West African militant group, Boko Haram, has been hampered by a failure among those countries to share crucial intelligence, sometimes even within their own security services, American and other Western officials say.

Western partners have balked as well. The Pentagon and American intelligence services have struggled at times to provide information quickly about Boko Haram militants to the African countries — Cameroon, Chad, Niger and Nigeria — without violating restrictions on what can be shared from spy satellite imagery or electronic eavesdropping within rules for not disclosing sources and methods.

Until recently, Western officials and analysts said, Britain and the United States provided only sanitized intelligence reports to the Nigerian military. The countries feared that more detailed information might be misused by an army that human rights groups say has committed abuses against civilians as it battles Boko Haram, which has pledged loyalty to the Islamic State.

A new intelligence “fusion centre,” created in Chad as part of a multinational task force, has only recently overcome budget and staffing shortfalls, as well as lingering mistrust among the participating countries, to help coordinate operations.

“The big unanswered question right now is how much are all those five countries that are participating going to collaborate and work effectively,” Col. Robert Wilson, who commands American Special Forces in North and West Africa, said in a recent interview, noting that Boko Haram moves easily across borders. Benin recently became the fifth country to join the coalition.

Even within the West African countries, interior ministries often do not share information about terrorist threats with their military counterparts.

In Cameroon, an elite special operations unit, the Rapid Intervention Brigade originally trained and equipped by Israel, now gets training and equipment from United States Navy SEALs and intelligence not handed over to other branches and units of its security services, Western analysts said. “It’s a confused mess,” said J. Peter Pham, the director of the Atlantic Council’s Africa Center in Washington.

American military and counterterrorism officials say intelligence sharing is a difficult issue, particularly outside established alliances. The United States confronted its own shortcomings after the Sept. 11, 2001, terror attacks, when it became clear that the F.B.I. and CIA each had information about the hijackers not shared with the other. In the wake of the Islamic State attacks in Paris and Brussels in the past year, the authorities in France and Belgium, as well as throughout Europe, are seeking to fill glaring gaps in intelligence sharing.

American intelligence and counterterrorism officials said it was a challenge to share sensitive intelligence with the West African allies fighting Boko Haram and other terrorist groups. The United States has different rules for what intelligence it shares with each country, and what one country can or cannot share with its neighbour — even though all are trying to fight a common regional enemy, Boko Haram.ier