UNITED NATIONS  - The UN Security Council on Thursday unanimously approved the first-ever ‘offensive’ UN peacekeeping brigade to battle rebel groups in the Democratic Republic of Congo.

A council resolution gave the force of more than 2,500 troops orders to “neutralize” and “disarm” armed groups in the resource-rich east of the country, which has been gripped by conflict for more than two decades.

The intervention brigade and surveillance drones to monitor the DR Congo’s borders with neighbors accused of backing the rebels will be operating by July, according to UN officials.

The force will launch UN peacekeeping operations into a new era, said diplomats who negotiated its preparation. Some key contributing nations to UN missions however say there are risks involved.

The resolution’s mandate to conduct “targeted offensive operations” has never been given to a peacekeeping mission before. It will act “in a robust, highly mobile and versatile manner and in strict compliance with international law” to “prevent the expansion of all armed groups, neutralize these groups, and to disarm them,” the resolution added.

The brigade and drones are part of a new UN campaign to end conflict in DR Congo’s border regions with Rwanda and Uganda.

Eleven African nations signed a UN-brokered accord last month pledging not to interfere in the affairs of their neighbors. Former Irish president Mary Robinson has been named as a UN special envoy for the Great Lakes region, leading political peace efforts.

The brigade will be made up of three infantry battalions, one artillery and one special force and a reconnaissance company with headquarters in the North Kivu provincial capital of Goma.

South Africa, Tanzania and Mozambique are the top candidates to provide the first troops for the brigade, diplomats said.

Rwanda, a temporary member of the Security Council, joined the body’s other 14 members in voting for the resolution.

Rwanda and Uganda have been accused by UN experts of backing the M23 rebels who briefly took Goma in November in an offensive which sparked the UN security rethink. Both have denied the charges.

Rwanda’s UN ambassador Eugene Richard Gasana called on the DR Congo government to make greater efforts to “tackle the deep-seated causes of conflict” in the country and also criticized “pre-conceived ideas of the past” which had seen Rwanda accused. “The Security Council and the UN have moved into new territory” with the intervention brigade, said Britain’s UN ambassador Mark Lyall Grant.

To succeed, Lyall Grant added, the whole mission in DR Congo must be “willing and able to implement fully the whole of the mission’s mandate.”

Guatemala, which has troops in the UN mission in DR Congo and is also a council member, “wavered” over whether to back the resolution, said its UN envoy Gert Rosenthal.

Guatemala is among countries which fear that the offensive brigade will make other peacekeepers a target of radical groups in DR Congo and other conflicts in which such a brigade could be introduced.

Pakistan, which also has troops in DR Congo, also has doubts. Its UN ambassador Masood Khan stressed that the intervention brigade should be a one-off operation.

Congolese and armed groups from neighboring nations, in particular the M23 rebels, have taken over large parts of the east of the country.

This month the M23 was wracked by infighting and hundreds of rebels loyal to warlord Bosco Ntaganda fled into Rwanda after being routed by a rival faction. Ntaganda is now in the custody of the International Criminal Court where he faces war crimes charges.