The contaminant has been linked to the deaths of more than 300 children in Africa and Asia
"The administration is withholding $255 million in assistance to Pakistan. There are clear reasons for this. Pakistan has played a double game for years," she told reporters at the United Nations. "They work with us at times, and they also harbor the terrorists that attack our troops in Afghanistan.
"That game is not acceptable to this administration. We expect far more cooperation from Pakistan in the fight against terrorism."