Carlotta Gall covers Afghanistan for the New York Times. Her new book is called The Wrong Enemy: America in Afghanistan, 2001-2014.
Highly critical of Pakistan, it offers new information about how Islamabad has helped the Taliban in Afghanistan, and how Pakistan's intelligence agency may have helped Osama bin Laden hide out in Abbottabad, Pakistan.
President Barack Obama, responding to the explosions at the Boston Marathon, says the United States does not know "who did this or why" but vowed that whoever is responsible "will feel the full weight of justice."
He said: "We will find out who did this and we will hold them accountable."
Obama made his remarks Monday evening from the White House about three hours after two explosions detonated near the marathon's finish line. At least three people were killed and more than 100 injured in the blasts.