Afghan and coalition forces clashed with militants Saturday in separate incidents in the east and south, killing 21 insurgents, officials said. The police and Taliban engaged in an hour-long gun battle in Khost province's Alishar district, said Wazir Padshah, a spokesman for the provincial police. He said NATO assisted with an airstrike, killing 11 militants. Three police were also wounded in the violence. Lt. Col. Angela Billings, spokeswoman for NATO's International Security Assistance Force or ISAF, confirmed that NATO launched an airstrike early Saturday, causing some insurgent casualties. She said there were no NATO or civilian casualties. On Saturday in Helmand, Afghan and coalition forces killed 10 suspected Taliban in a clash and airstrike, the coalition said in a statement.