Four US soldiers were killed in a bomb attack in Afghanistan Tuesday, Nato said, bringing the toll of Americans to 21 dead since Friday. Nato spokesman James Judge confirmed to a foreign news agency that four American soldiers were killed in eastern Afghanistan by an improvised explosive devise (IED). The deaths bring to 484 the total number of foreign troops killed in the Afghan war this year, compared to 521 for all of 2009, according to a foreign news agency tally based on that kept by the independent icasualties.org website. The deaths come a day after eight Nato troops seven of them American were killed in similar bomb attacks in southern Afghanistan.