The United States is reportedly withholding at least $3 billion in an ongoing dispute with Pakistan over the free passage of NATO supply convoys and the U.S. refusal to apologize for a November air strike that mistakenly killed 24 Pakistani troops. Speaking in Afghanistan, Defense Secretary Leon Panetta said the United States is “reaching the limits” of its patience with Pakistan.

Defense Secretary Leon Panetta: “We are reaching the limits of our patience here. And for that reason, it is extremely important that Pakistan take action to prevent this kind of safe haven from taking place and from allowing terrorists to use their country as a safety net in order to conduct their attacks on our forces.”

Panetta’s visit to Afghanistan came one day after an estimated 18 Afghan civilians were killed in a U.S.-led NATO bombing.