U2's past decade has been all about looking back. First, the companion albums Songs of Innocence (2014) and Songs of Experience (2017) arrived as meditations on life, mortality and the past; then 2023's Songs of Surrender brought the trilogy to an end in the most fitting of ways: by reworking 40 songs, sometimes to drastic effect, from their vast catalog. (During this same period, the band also performed tours and concerts focused on their classic albums The Joshua Tree and Achtung Baby.)

They continue this path on How to Re-Assemble an Atomic Bomb, not new recordings but a 10-song collection pulled from the sessions for their 11th album, 2004's How to Dismantle an Atomic Bomb, which was marked by its notably harder rock approach to U2's music. At the time it was a louder version of the spiritual uplift of 2000's All That You Can't Leave Behind; on its 20th anniversary, the album sounds like a brutally direct reawakening following the band's occasionally wayward '90s.

While How to Re-Assemble an Atomic Bomb won't change anyone's perception of the 2004 record, these associated pieces give a more distinct glimpse of mid-'00s U2 in the studio. Often more disordered than the tracks on the released album, the newly recovered songs - all previously unreleased - prove the band wasn't quite ready to abandon their '90s risk-taking.

READ MORE: How U2 Introduced Themselves With the Punky and Thoughtful 'Boy'

Despite the back-to-basics nature of All That You Can't Leave Behind and How to Dismantle an Atomic Bomb, U2 continued to look ahead four years into the new millennium; Bono's opening line on How to Re-Assemble an Atomic Bomb - "My cell is ringing, no ID / I want to know who's calling," from the jagged "Picture of You (X+W)" - has lost little relevance over two decades. The guitars-to-11 rattle and hum throughout the album fully complements the original's volume-pushed offerings.

But How to Re-Assemble an Atomic Bomb isn't so much an alternate take on How to Dismantle an Atomic Bomb as it is another view of the same period. Its best songs could easily find a place on the 2004 album: "Luckiest Man in the World" (leaked online two decades ago as "Mercy"), the chest-beating "Country Mile," the skittering disco of "Happiness." Only the post-punk gurgle of the dispensable instrumental "Theme From the Batman" and "All Because of You 2," a different version of the Dismantle album track, reveal Re-Assemble's leftovers origins. Otherwise, this is U2 furiously working off their comeback high.

Top 40 Albums of 1983

Pop, new wave, punk and rock collided in a year that opened possibilities.

Gallery Credit: Michael Gallucci

More From Ultimate Classic Rock