A NATO-led airstrike in Afghanistan that targeted insurgents Saturday is now under investigation for reportedly killing 12 children and two women, and Afgan President Hamid Karzai issued a strong rebute to the alliance. Calling it his "last warning," a spokesman said Karzai called the attack a "great mistake" on the part of NATO. The strike occurred in Helmand province, a Taliban stronghold that has been an area of conflict in recent weeks due to the militant group's spring offensive. According to NATO, the airstrike was intended for insurgents who attacked Afghan security troops. Another suicide bombing in Afghanistan yesterday killed top police chief General Daud, and officials said these attacks signal that the Taliban is not letting up in spite of NATO's anti-terrorist efforts.