Two more American troops were killed in Afghanistan on Tuesday, the military said, extending a spike of bloodshed into a second day and pushing the NATO losses in the country to 23 in just over a week. The latest deaths came as insurgents step up bombings and other attacks ahead of a major NATO operation in the Taliban stronghold of Kandahar that Washington hopes will turn the tide of the nearly 9-year-old war. Monday was the bloodiest day this year for international forces in Afghanistan, when seven American troops, two Australians and a French Legionnaire were killed in five separate insurgent attacks in the south and east of the country. Two civilian contractors training police, an American and a Nepalese, also died in a brazen suicide attack Monday in the southern city of Kandahar. NATO said two service members were killed Tuesday in a makeshift bomb blast in southern Afghanistan, and the U.S. military confirmed they were Americans.