From the start, it was clear that U2 could create impressive music. The jagged guitar riff and thundering drone that launched "I Will Follow," and the rest of their 1981 debut album, Boy, was eloquent and visceral. It was also musically uncomplicated; these four young Dubliners had an instinctive sense for making the most out of simple shifts in dynamics and elementary voicings, and it gave their sound a rough, exhilarating grandiloquence. The only problem was that once U2 caught a listener's attention, they had little to say. Boy waxed poetic on the mysteries of childhood without really illuminating any of them; October, its successor, wrapped itself in romance and religion but didn't seem to understand either. Without a veiwpoint that could conform to the stirring rhythms and sweeping crescendos of their music, U2 often ended up sounding dangerously glib.

With their third album. War, U2 have found just such a perspective and with it, have generated their most fulfilling work yet. War makes for impressive listening, but more important, it deals with a difficult subject in a sensible way. That subject is the sectarian strife in Northern Ireland, or what the Irish call "the troubles." U2 are not the first group to play soldiers with this topic; Belfast's Stiff Little Fingers have dealt with the problem explicitly, the Clash somewhat more obliquely. But no one has caught the paradox between stance and action so accurately.

"Sunday Bloody Sunday," which opens the album, apparently addresses Bloody Sunday, a 1972 incident in which British paratroopers killed thirteen civilians in an illegal civil-rights demonstration in Londonderry. As an acoustic guitar and a sizzling hi-hat build tension, vocalist Bono sings, "I can't believe the news today . . . . " The band slips into some lush, sustained chords as he wonders, "How long? How long must we sing this song?" then jumps back into a militant, jagged dance beat.

It's great drama, and it lends a certain amount of credence to the song's wistful chorus, "Tonight, we can be as one. Tonight!" But Bono tips his hand when he sings the urgent disclaimer, "I won't heed the battle call/It puts my back up, puts my back up against the wall."

What Bono and the band are saying, then, is that it's pointless to take irresponsible risks when confronting irresponsible authority - but one must still take some sort of stance.

Unlike the Clash, who wrestle with imperialist foreign policy, or the Gang of Four, who try to transfer a Marxist dialectic to the dance floor, U2 don't pretend to have the answers to the world's troubles. Instead, they devote their energies to letting us know that they are concerned and to creating an awareness about those problems. And not only is that refreshing, but it makes sense, because U2 understand that it's the gesture, not the message, that counts.

Complementing U2's lyrical growth is a newly developed dark sense of humor, which the band uses to striking effect throughout the album. "Seconds," for example, opens with a sleepy funk riff driven by a cheerful toy bass drum. It's a pleasant juxtaposition, but as the song's subject matter becomes clear - the insanity of nuclear blackmail, where, as Bono puts it, "the puppets pull the strings" - you realized that this jolly noise-maker is no more an innocent plaything than is the one in Gunter Grass' The Tin Drum. Similarly, "New Year's Day" includes the wisecrack, "So we are told, this is a golden age/Gold is the reason for the wars we wage" - a remark far wiser than it at first seems.

Yet War isn't all jaded ideals and sour wit, for as Bono makes his pronouncements, his vocalise reveals the full flower of U2's melodic abilities. In between the bitter humor of "Seconds," he breaks into joyous flights of wordless melody, his voice soaring in multi-tracked polyphony over the song's slippery rhythms. "Surrender" is lighter still, thanks to its airy melody and the Edge's coolly sustained guitar. In fact, this song is the one instance where the music says more than lyrics ever could, because hearing Bono's blissful tenor floating over the backing vocals (courtesy of Kid Creole's Coconuts is a better definition of "Surrender" than anything in Webster's.

Generally, the album's musical strengths are largely the product of well-honed arrangements and carefully, balance dynamics. Even as the Edge spins increasingly sophisticated guitar lines, he maintains the minimalist bluntness that sparked Boy. And while bassist Adam Clayton and drummer Larry Mullen Jr. have swung to more dance-oriented rhythms. their songs hurtle along with the sort of brusque purposefulness more frequently associated with punk.

U2 may not be great intellectuals, and War may sound more profound than it really is. But the songs here stand up against anything on the Clash's London Calling in terms of sheer impact, and the fact that U2 can sweep the listener up in the same sort of enthusiastic romanticism that fuels the band's grand gestures is an impressive feat. For once, not having all the answers seems a bonus.