AFGHANISTAN AND PAKISTAN
Length: 1,500 miles
Why it's so dangerous: Lawlessness, al Qaeda and other militant groups, drone strikes.
Background: The border area between Afghanistan and Pakistan has long been one of the most dangerous and lawless places in the world. Kabul refuses to recognize the 1,500-mile-long Durand Line as an international border with Pakistan, instead claiming for itself the Pashtun territories in northwest Pakistan that comprise the Federally Administered Tribal Areas (FATA) and parts of Khyber Pakhtunkhwa province. According to the United Nations, more than 1.7 million registered Afghan refugees live in Pakistan, a legacy of decades of instability, occupation, and civil war. The ongoing border frictions are due in large part to tribal allegiances that span the century-old frontier. Forty percent of Afghanistan's population is made up of Pashtuns; in Pakistan, the figure is about 15 to 20 percent. Many Pashtun nationalists on both sides of the Durand Line continue to demand an independent state of Pashtunistan.
Today: Incidents of violence have increased on both sides of the Pakistan-Afghanistan border since the U.S.-led invasion of Afghanistan -- and the border region itself has provided a safe haven for a witches' brew of militant groups fighting against both the U.S. forces and the Pakistani state. U.S. President Barack Obama's administration has ramped up the use of drone strikes to target al Qaeda-linked groups along the border. As of June 23, there have been 253 drone strikes since 2004, with an estimated death toll between 1,557 and 2,464, according to the New America Foundation.
Violent border clashes between Pakistani and Afghan forces have also been an ongoing problem since May 2007, with numerous soldiers killed on both sides. On June 20, after an assault by Pakistani forces drove a group of militants across the border into eastern Afghanistan, the Afghan side accused Pakistan of shelling Afghan villages. Each country continues to blame the other for failing to crack down hard enough on militants along the porous borderline. The continuing violence threatens to make things more difficult for Washington as it prepares a gradual withdrawal of U.S. troops from Afghanistan.