The head of the army in the Democratic Republic of Congo says he has given up all hope of a peaceful solution to the conflict in eastern Congo.
Gen Nkunda says he is protecting DR Congo's Tutsi community
General Dieudonne Kayembe said force was now the only way to deal with dissident General Laurent Nkunda.
Fighting has continued in the North Kivu province for a third day, with government troops using heavy artillery against rebel forces in Rugari.
Gen Nkunda has threatened UN troops, accusing them of backing the army.
The United Nations peacekeeping mission in DR Congo (Monuc) says the army has been sending reinforcements to the region ahead of a possible major offensive against Gen Nkunda.
The BBC's Arnaud Zajtman in the capital, Kinshasa, says the army has suffered military setbacks in previous offensives against the rebels.
Observers say the army seems to be trying to target Gen Nkunda's supply lines near the Rwandan border.
Rugari is 30km (19 miles) from the North Kivu regional capital, Goma, towards the border.
Rwanda has always denied claims it backs Gen Nkunda, who is an ethnic Tutsi, like most of the Rwandan leaders.
He argues he is trying to defend his community against armed Hutu groups, some of whom crossed into DR Congo after the 1994 Rwandan genocide.
"Now that all attempts to use persuasion, to use peaceful means have been used, I am here in Goma to set up plans for military force," Gen Kayembe said.
"We are doing the military planning with Monuc."
But this has prompted Gen Nkunda to accuse the UN of taking sides.
The UN mission, "hitherto perceived as a guarantor of peace and international law... and a facilitator in the armed conflicts between Congolese, has taken the serious decision to side wholeheartedly with the FARDC [army] in its war against the CNDP [Gen Nkunda's forces]," he said in a statement sent to the AFP news agency.
Monuc "will have to assume fully all the consequences resulting from this choice", he said.
The army has deployed 20,000 men in North Kivu since August.
Gen Nkunda is thought to have between 6,000 and 8,000 men under arms but has failed to honour pledges to disarm his men and re-integrate them into the DR Congo armed forces.
Some 375,000 people have fled fighting in eastern DR Congo this year, on top of 800,000 who were already displaced.