The world has seen a steady decrease in the number of nuclear warheads over the last five years due in large part to the U.S. and Russia reducing their inventories of nuclear arms under their bilateral arms reduction and limitation treaty, according to a Swedish security think tank.

In its Yearbook 2014, the Stockholm International Peace Research Institute also said that there was an emerging consensus among experts that North Korea has produced a small number of nuclear weapons. It put the number of Pyongyang’s nuclear warheads at 6-8.

While Russia and the U.S. still account for more than 93 percent of all nuclear weapons, all five recognized nuclear weapon states ― China, France, Russia, the U.K. and the U.S. ― are either deploying new nuclear weapons delivery systems or have announced programs to do so.

The think tank pointed out that nuclear reduction is being carried out slowly, while countries with nuclear weapons continue to modernize their nuclear forces.