International efforts to stop North Korea from acquiring nuclear weapons have been “one big collective failure,” the chief of the International Atomic Energy Agency (IAEA) said this week, warning that Pyongyang is now assembling a “considerable nuclear arsenal.”

During a lecture at Australia National University, IAEA Director General Rafael Grossi also noted expectations that the DPRK could conduct another nuclear test “any day,” after the country began restoring tunnels at its nuclear test site earlier this year.

“Up until 2006, North Korea did not have nuclear weapons,” Grossi saidTuesday. “A number of initiatives … failed,” he added, citing the