Halts sessions for Amnesty International tour

For their fifth album, The Joshua Tree , the band wanted to build on The Unforgettable Fire ‘ s textures, but instead of experimentation, sought a harder-hitting sound within the limitation of conventional song structures. Realising that “U2 had no tradition” and that their knowledge of music from before their childhood was limited, the group delved into American and Irish roots music . Friendships with Bob Dylan , Van Morrison , and Keith Richards motivated Bono to explore blues , folk , and gospel music and to focus on his skills as a songwriter and lyricist. U2 halted the album sessions in June 1986 to play as a headline act on the Conspiracy of Hope benefit concert tour for Amnesty International . Rather than distract the band, the tour invigourated their new material. The following month, Bono travelled to Nicaragua and El Salvador and saw first-hand the distress of peasants affected by political conflicts and US military intervention. The experience became a central influence on their new music.