Congolese troops are fighting Ugandan rebels in the eastern region of the Democratic Republic of Congo in clashes that have killed two dozen combatants and forced thousands of civilians to flee, military and aid officials said Thursday. They are the first clashes in years between the army and the Allied Democratic Forces-National Army for the Liberation of Uganda, a rebel group trying to set up an Islamic state in Uganda. The army said it attacked the rebels in Eringite in North Kivu Province late on Wednesday. Gen. Vainquer Mayala said that the army had killed 22 rebels and that three of its soldiers had been killed.