US-led coalition and Afghan troops killed up to 21 suspected Taliban militants in two separate clashes in southern Afghanistan, and a roadside blast killed four Afghan soldiers in the east, officials said Tuesday. In the Taliban-held Musa Qala district of Helmand province, militants ambushed the joint US-Afghan force Monday, a coalition statement said. The joint force fought back, targeting militants who were using several compounds and trenches for cover, the statement said. It said about a dozen militants were killed in the clash. Militants have been running Musa Qala since last year's controversial peace deal between local elders and Afghan government officials, supported by British troops in the province. The deal effectively turned over Musa Qala town and surrounding areas to Taliban control.