With "The Joshua Tree", the U2 pendulum swings back to America again. If "The Unforgettable Fire", partially through Brian Eno's guidance, was their most European record, this, their fifth studio album, turns their sights again on the Big Country, sometimes howling off in pursuit of the ghosts that possess the American soul. In time, it may he reckoned their most influential album to date.

It also clarifies how U2's vocation has become the revival and renewal of rock and the recovery of its most romantic values. Between the increasingly mercenary implosion of hard rock into a static vaudeville routine and the intervention of pop dance-floor values, rock has lost its lustre and mystique of genuinely redeeming passion. From one angle, "The Unforgettable Fire" can now seem a strategic retreat, to regroup, reassess the situation and gain new ammunition. But if that album necessarily circumvented some of the issues, "The Joshua Tree" returns to a frontal assault.

It is also the second successive album where U2 strip away the skins of their previous styles. Only the opening "Where The Streets Have No Name", "In God's Country" and, possibly, elements of "One Tree Hill' preserve previously identifiable hallmarks. Otherwise, The Edge's guitar has developed its own military tendency, homing in on the legacy of Jimi Hendrix and Led Zeppelin, while the group's new commitment to songs finds both Bono and the rhythm section contending on dance-floors they never previously frequented, with complete confidence.