Afghan security forces carried out the operation Monday in the Washir district, Khaama Press reported. Daud Ahmadi, a spokesman for the provincial governor, said 20 militants were killed and 10 injured.
One Afghan soldier was killed Monday in Kandahar and three injured.
Afghan forces seized caches of weapons and ammunition in Kandahar and Khost provinces.
In Helmand province, a U.S. Marine, Staff Sgt. Joseph H. Fankhauser, 30, of Mason, Texas, was killed on Sunday by an improvised explosive device, the U.S. military said.