WASHINGTON, Aug 26 (Reuters) - The count of U.S. troops believed to have been killed in Thursday"s Kabul blasts has increased to 12, according to U.S. officials citing initial information that can change. Earlier a U.S. official told Reuters that at least 10 American military members were believed killed in the explosions at a gate at the Kabul airport where the United States is mounting a massive evacuation and at a nearby hotel. (This story refiles to lower case "troops" in headline)