The suspect packages sent to Army Careers offices were in A4-sized envelopes, postmarked Ireland, contained black powder which was explosive and if ignited would have caused flash burns, ITV News' Juliet Bremner understands.
However, the officers who discovered the suspect packages are not certain that they would have exploded.
This indicates that Irish dissident groups were very likely behind the attack.
More top news
The singer demanded a fan stop using a tripod during a live show and advised her to enjoy it "in real life".
Johnny Depp's band the Hollywood Vampires are due to play in Stockholm, Sweden, but face calls for the gig to be boycotted.