As the protests over the burning of Korans at a U.S. base claimed their first U.S. casualties in Afghanistan, President Barack Obama sent a letter of apology to Afghan President Hamid Karzai, Karzai's office reported on Thursday. Obama offered his "sincere apologies," according to Karzai's office. The whole text of the letter hasn't come out, but from what Karzai's office released, it sounds pretty unqualified -- a genuine mea culpa from the Commander in Chief. "The error was inadvertent; I assure you that we will take the appropriate steps to avoid any recurrence, to include holding accountable those responsible," Obama reportedly wrote. The president sent the letter, via U.S. Ambassador Ryan Crocker, the same day a man in an Afghan National Army uniform shot and killed two U.S. soldiers at a base in eastern Afghanistan.