Afghanistan:Americans were patrolling with Afghan soldiers when their vehicle struck a bomb

roadside bomb killed four U.S. troops in southern Afghanistan on Tuesday, inflicting the year's deadliest single attack on international forces a week after Washington set plans to send reinforcements. An Afghan civilian working with the Americans also died.The Americans were patrolling with Afghan soldiers when their vehicle struck a bomb Tuesday afternoon, the U.S. military said in a statement. The military withheld identities of the dead and the attack's location pending notification of relatives.
The previous deadliest attack on U.S. troops this year was an explosion in Zabul province in January that killed three Americans.Twenty-nine U.S. military personnel have died in Afghanistan this year, far surpassing the eight Americans killed in the first two months of 2008. A total of 654 have died since the U.S.-led offensive that ousted Afghanistan's Taliban regime in late 2001.Taliban militants have increased attacks the last three years and now hold sway in large areas of countryside, leading the Obama administration to promise an intensified focus on defeating Islamic extremists in this region.

President Barack Obama announced Feb. 17 that he had decided to send 17,000 more soldiers and Marines to Afghanistan, adding to the record 38,000 already fighting a strengthening insurgency. Many of the U.S. troops now operate in Taliban strongholds in the dangerous south.

Obama's order should would put several thousand troops in place in time for the increase in fighting that usually occurs with warmer weather and ahead of Afghan national elections scheduled for August.U.S. officials said last week even more troops could be sent later, but that decision would not be made until a broad review of policy for dealing with militants in Afghanistan and Pakistan. The review should be completed around the end of March, which coincides with a NATO summit.The American commander in Afghanistan, Gen. David McKiernan, has been seeking as many as 30,000 additional U.S. troops to counter the resurgence of the Taliban militants and protect Afghan civilians.U.S. commanders say they want to bolster combat units and trainers in the south with enough new troops to stem insurgent violence without becoming an occupying force that would alienate Afghan civilians.In other violence, the U.S. military said coalition and Afghan troops killed 16 militants Monday after insurgents attacked their convoy in southern Helmand province. There were no other reports of casualties, the statement said.