* U.N. Security Council visits Goma in eastern Congo
* Two other armed groups pose as great a threat as M23 -U.N.
* Millions have died during decades of conflict in Congo
After an aggressive new U.N. brigade in eastern Democratic Republic of Congo scored a military victory over M23 rebels and forced them back to peace talks, U.N. peacekeepers are now turning their focus to two other equally dangerous armed groups.
During a visit by U.N. Security Council ambassadors to the eastern capital of Goma on Sunday, U.N. officials said that while M23 had garnered global headlines, just as great a threat was posed by the Democratic Forces for the Liberation of Rwanda (FDLR) and the Islamist group Allied Democratic Forces (ADF).
"If we do not manage by one way or another to neutralize, disarm, demobilize those groups, we are not very hopeful (for sustainable peace)," said Ray Torres, head of the U.N. peacekeeping mission, known as MONUSCO, in North Kivu province.
He said that many of the other 39 armed groups in eastern Congo had justified their existence as rivals to M23 and FDLR.
Millions of people have died from violence, disease and hunger since the 1990s as rebel groups have fought for control of eastern Congo's rich deposits of gold, diamonds, copper, cobalt and uranium.
The Security Council earlier this year created the so-called Intervention Brigade within MONUSCO, an assertive new step for U.N. peacekeeping, which for years has been criticized in the region for inaction and failing to protect civilians.
Malawian troops started deploying last week to join South African and Tanzanian soldiers in the 3,000-strong Intervention Brigade, officials said. MONUSCO has a total of about 20,000 troops spread across the vast Central African state.
Standing on a hilltop - known as Kibati Three Towers - just north of Goma, Torres told the 15 Security Council envoys that was where Congolese troops, aided by the Intervention Brigade for the first time, had beaten back M23 rebels in August.
"The operations that took place here changed substantially the situation and the set up in North Kivu," said Torres. Not only had M23 returned to peace talks with the Congolese government, but defections had increased and the operation had sparked a number of peace initiatives with other armed groups, he said.
Despite the initial success of the Intervention Brigade, however, Security Council envoys came up against what they called "excessive expectations" for the force during talks with Congolese officials in Kinshasa on Saturday and with civil society leaders in Goma on Sunday.
"I'm sure they're expecting too much (of the brigade)," said British Ambassador Mark Lyall Grant. "It's been a good start, it was an experiment the Security Council decided to take because of our concerns to protect civilians in a place and at a time when they hadn't been protected for a very long period."
QUESTIONS OVER SUPPORT
One in six people in North Kivu have been displaced. The council envoys visited Mugunga 3 camp, which is home to more than 16,000 people internally displaced. Camp resident Amnazo-Sharv told them she believed it was up to the U.N. peacekeepers to clear away all the armed groups in eastern Congo.
"Once MONUSCO has finished that task we will be assured peace has been restored," said a visibly upset Amnazo-Sharv, speaking through a translator, after she threw herself to her knees in front of the ambassadors to ask for help.
Azerbaijan Ambassador Agshin Mehdiyev, president of the council for October, told a news conference in Goma that while the international community would continue to support Congo, "at the end of the day you are Congolese, you're responsible for the protection of your territory and your people."
Eastern Congo has long been one of Africa's bloodiest battlegrounds. The roots of this conflict lie in the 1994 genocide in neighboring Rwanda, where Hutu soldiers and militia killed 800,000 Tutsis and moderate Hutus.
Many of those responsible for the genocide fled into eastern Congo along with two million Hutu refugees. Many "genocidaires" now fight for the FDLR. Rwanda has accused Congolese troops of collaborating with the FDLR, a charge Kinshasa has denied.
U.N. experts have repeatedly accused Rwanda of backing the 18-month-long rebellion by M23, a claim the Rwandan government has fiercely rejected.
"We need to study much more the access, not only of M23 and FDLR, but the access of all the groups to weapons and ammunition," MONUSCO force commander General Carlos Alberto dos Santos Cruz told the Security Council ambassadors. "We need to know more on the financial support for them, how they get these weapons, ammunition and more resources, including uniforms."
Thick forests, rugged terrain and the scarcity of roads on Congo's eastern border with Rwanda and Uganda have complicated efforts by Congolese troops and U.N. peacekeepers to control the resource-rich area.
Santos Cruz said that while the U.N. force needed more helicopters, the expected arrival next month of an unarmed surveillance drone would be a great boost to capabilities.
It will be the first time the United Nations has used such equipment and, if the trial surveillance in eastern Congo is successful, officials and diplomats hope the drones could also be used by missions in Ivory Coast and South Sudan.
Torres expressed particular concern about the ADF, which he said was establishing and strengthening its position.
"It's very strongly ideologically based, it's an extremist Islamist group that is developing a network of businesses that indicates to us that they are planning to stay," Torres said.
The Ugandan government says the ADF is allied to elements of Somalia's al Shabaab movement, an al Qaeda-linked group, but Torres said not enough is known about them and he has established a MONUSCO task force to learn more about it.