Nuclear-armed states are deploying more warheads on operational systems, heightening conflict risks despite declining overall stockpiles, researchers at SIPRI reported. Geopolitical rivalries and arms build-ups threaten to reverse decades of nuclear arsenal reductions.

The world’s nuclear-armed states are increasingly moving warheads from storage onto operational delivery systems, raising the risk of conflict despite a gradual decline in overall stockpiles, researchers warned on Monday. SIPRI said geopolitical rivalry and a new arms build-up could reverse decades of reductions in nuclear arsenals.