“Any use of such weapons - or if we think that those weapons are about to be used…the North Koreans will be held to account,” Powell said on the sidelines of the Russia Forum 2013, adding the United States has “the capacity to destroy that regime.”

The threat from Pyongyang should taken seriously, he said, but “we shouldn’t get hysterical” about it because “in my own judgment, I don’t think they yet have a nuclear weapon that is deliverable.”

“I hope sooner or later they will come to their senses,” he said. “The regime would be committing suicide if it used those weapons.”

Tensions have risen sharply on the Korean Peninsula since December, when North Korea tested a long-range Taepodong 2 missile, and in February carried out its third nuclear test.

The UN responded with sanctions. The start of joint military exercises between South Korea and the United States last month further irritated the North, which threatened to carry out a nuclear attack on the US mainland, as well as on US forces in the region.