The Afghanistan–Pakistan barrier refers to the border barrier being built by Pakistan along its border with Afghanistan, otherwise known as the Durand Line. The purpose of barrier is to prevent terrorism, smuggling, illegal immigration and infiltrations across the approximately international border between Afghanistan and Pakistan. Major-General Shaukat Sultan, a former Pakistani military spokesman, said the move was necessary to block the infiltration of militants across the border into Pakistan. The initially proposed fortifications and fence, about in length, was backed by the United States in 2005. Construction on the border barrier unilaterally began in March 2017 following a series of deadly and costly clashes between Pakistani security forces and Afghan-aligned militants in Pakistan's tribal areas that greatly intensified hostilities in the War in North-West Pakistan.