GOMA, Democratic Republic of Congo (Reuters) - Congo and Uganda are planning a joint military operation against a Congo-based Ugandan rebel group blamed for an attack that killed 15 United Nations peacekeepers, army officials from the two countries said on Wednesday. Fighters from the Allied Democratic Forces are suspected of being behind the Dec. 8 assault on a base manned by Tanzanian U.N. troops in the Democratic Republic of Congo s troubled eastern borderlands.  The attack, which also killed five Congolese soldiers and wounded another 53 peacekeepers, and came amid a rising wave of violence in the mineral-rich area.  The commanders of the ADF are Ugandan citizens. A mechanism will be outlined so the two armies can share intelligence and carry out a coordinated operation,  said General Marcel Mbangu Mashita, a senior Congolese army commander in the east. Representatives from the two armies met in the Congolese border town of Kasindi last week. Under the plan, Ugandan troops will not cross over into Congolese territory but instead be concentrated along the border.  (The Ugandan army) is reinforcing security on the common border with Congo in order to dissuade any attempt by the ADF to cross over and attack targets of interest in Uganda,  Ugandan army spokesman Brigadier Richard Karemire said. Congo s U.N. peacekeeping mission, MONUSCO, has pledged to track down those responsible for the attack on its base. But it was not involved in the bilateral talks between the Congolese and Ugandan officials. Rival militia groups control parts of eastern Congo, long after the official end of a 1998-2003 war in which millions of people died, mostly from hunger and disease.  Congo and Uganda were enemies during that conflict and, in the years since, relations between the two countries have at times been strained. Increased militia violence this year in the center and east comes as Congo faces a political crisis linked to President Joseph Kabila s refusal to step down when his mandate expired last December. The ADF is an Islamist group that has long been active along the border and has been blamed for a wave of massacres there over the past two years. Since its leader Jamil Mukulu was arrested in 2015, it has been headed by Musa Baluku.  General Mashita said previous Congolese operations had succeeded in eliminating around a third of the ADF s top commanders, but added that its ranks had been bolstered by escaped prisoners after a major prison break in June. 