The UN mission in Democratic Republic of Congo has started to deploy unarmed surveillance drones to monitor rebel activity near the forested borders with Rwanda and Uganda.
This is the first time any UN mission has deployed drones.
The first two were launched from the eastern city of Goma, which was last year briefly occupied by M23 rebels.
The UN force in DR Congo played a key role last month in defeating the M23 but other militias still operate.
The BBC's Maud Jullien in eastern DR Congo says it has long been suspected that various armed groups in the North Kivu province get their supplies from neighbouring countries.
Both Rwanda and Uganda have denied repeated accusations that they supported the M23 rebels, which were recently defeated with the help of the 22,000-strong UN mission in DR Congo - the world's largest.
UN peacekeeping chief Herve Ladsous told the BBC that the drones, or "unarmed, unmanned aerial vehicles" would be the "tool of choice" to monitor the activities of armed groups and the movement of civilians.
"We need to get a better picture of what is happening," he said.
He said that if they were successful in DR Congo, they could also be used in other UN peacekeeping missions.
The first two drones were made by an Italian firm, Selex ES, a subsidiary of the Italian giant Finmeccanica, reports the AFP news agency.
UN officials expect three more drones to be deployed in the coming months.
They will be deployed across North Kivu, which has been one of the areas worst affected by two decades of conflict in the mineral-rich eastern DR Congo.
They have a range of 250km (155 miles) from their base in Goma.
Congolese Defence Minister Alexandre Luba Ntambo says the drones will help the army against rebel groups.
"Once we know exactly where they are hiding, our operations will be much more efficient," he said.
Despite the defeat of the M23, numerous other armed groups still roam eastern DR Congo, including the FDLR, whose leaders are accused of involvement in the 1994 genocide in Rwanda.