Barack Obama has condemned Saturday's suicide attack in northwest Pakistan. At least 43 people were killed in the bombing at a World Food Programme distribution centre in Bajaur.
In a statement released by the White House, the US president said: "The United States stands with the people of Pakistan in this difficult time, and will strongly support Pakistan's efforts to ensure greater peace, security and justice for its people."
The Pakistani Taliban claimed responsibility for the attack, through its spokesman, Azam Tariq.
The spokesman suggested the victims may have been targeted because most of them belonged to the Salarzai tribe, which was among the first to set up a militia - known as a lashkar - to fight the Taliban in 2008.
Other tribes later formed similar militias to resist the Taliban fighters.
"All anti-Taliban forces, like lashkars, army and security forces, are our target," he said.
"We will strike them whenever we have an opportunity."
Al Jazeera's Kamal Hyder reports on the attack in Bajaur.