Yaounde - Boko Haram is increasingly a regional threat and the battle against the Nigerian Islamist sect is meant to be a regional campaign, but that's not the way it feels for Cameroon's soldiers on a desperate frontline.
"We are fed up with fighting this war all alone," a Cameroonian officer said as he described his army's resistance against Boko Haram and the lack of military support from neighbouring governments.
"The attacks against our territory come from a neighbouring country, which calls itself sovereign and does nothing," said a defence ministry official who asked not to be named.
The official complained that Cameroon had been drawn into a "proxy war" against Boko Haram, which has stepped up massacres of villagers in Cameroon's far north at the same time as killing and maiming in Nigeria.
Also read: Cameroon battles to keep youths out of Boko Haram
Last Friday alone, suspected Boko Haram fighters slaughtered at least 120 people in a suicide bomb and gun attack on the central mosque in the north Nigerian city of Kano.
Cameroon's army has been stretched in its attempt to check cross-border incursions by the group, whose name loosely translates as "Western education is a sin".
And that task has become harder as Boko Haram fighters grow in strength and ambition.
"Each time Boko Haram captures a town in Nigeria, it recovers all the military equipment there. So now they really have heavy weaponry," a source in the intelligence services said.On our own
In mid-October, Islamist fighters equipped with a tank and a booby-trapped car bomb laid siege to an army position in Amchide, a town that straddles the frontier, while also attacking Limani in the north.
"Fighting of rare violence" left 107 Boko Haram members and eight Cameroonian soldiers dead, the defence ministry said, while a police officer told AFP that before the battle, the militants "cut the throat of many civilians, 30 at least".
"We're on our own at the front," said a commander of the elite Israeli-trained Rapid Intervention Brigade (BIR).
Across the border in northeastern Nigeria, Boko Haram controls swathes of territory abandoned by the authorities, leaving the local population to its fate.
In Amchide, Cameroon's army faces enemy forces dug in around the far end of a bridge marking the border. Boko Haram routed local Nigerian troops and now is only separated from Cameroonian soldiers by a dusty and deserted no man's land.
When 500 Nigerian troops crossed into Cameroon in early August, the army command said the soldiers were "charging through the borders in a tactical manoeuvre".
But Cameroon is getting used to seeing Nigerian soldiers arriving for a quite different reason, fleeing Boko Haram, which is estimated to have killed more than 13,000 people since 2009.
At the same time, Cameroon has come under criticism from neighbouring countries and former colonial power France for not doing enough to stop Boko Haram from using its territory as a rear base for its war in Nigeria.Operation Alpha
The 2013 abduction within Cameroon of French national Tanguy Moulin-Fournier and his family by Boko Haram led to a change in strategy.
The hostages were freed, as were two Italian priests and a Canadian nun seized early this year. But Cameroon's President Paul Biya ordered substantial military reinforcements to the far north to tackle the armed fundamentalists in "Operation Alpha".
Also read: Cameroon's army faces Boko Haram on Nigerian
Some 2,000 men were deployed, but security officials stress that more troops are needed to control the long, porous border.
"We hope that aid from here and there, from the international community, will enable us to bring the swiftest possible end to this aggression," government spokesman Issa Tchiroma Bakary said recently.
During talks in Paris in May, Nigeria and three neighbouring countries, Cameroon, Chad and Niger, came up with a battle plan.
They agreed to share information and coordinate their intelligence work, to keep joint watch over their borders and to develop the capacity to intervene swiftly in response to threats.
Each of the four countries pledged to send 700 troops to the Lake Chad region, where their borders all come close together. However, that promise has yet to be fully honoured.
"Cameroon has already sent 300 men from the navy. Chad and Niger are well disposed to provide troops, but it's less certain where Nigeria is concerned," a Cameroonian military source said.