KABUL, Afghanistan — Military officials today reported the year's first U.S. combat casualties in Afghanistan -- four troops killed a day earlier in the country's violent south.
In addition to the Americans killed in Sunday's blast, a British soldier died in a separate explosion, also in the south.
Roadside bombs are the No. 1 killer of Western forces in Afghanistan, and have become the signature weapon of the Taliban and other insurgents.
American troop deaths in Afghanistan surged during 2009, doubling from their levels in the previous year. Commanders have warned that the Obama administration's coming troop buildup will likely bring with it an increase in casualties, in part because the new forces will be pushing into areas of the country where the insurgents have until now held sway.