Talk of pre-emptive strikes against the North has come to the fore after US Secretary of State Rex Tillerson said last week that diplomacy failed to disarm the North and the US is considering a new range of options, including a military option.

"Tillerson's warning did signal that the Trump administration is taking US policy toward North Korea in a new direction ? that we may be serious about abandoning engagement and willing to pursue containment through military action," Gallucci said.

Gallucci, currently a professor of diplomacy at Georgetown University, said that the US could launch attacks as part of either a "preemptive" strike in response to an imminent attack or a "preventive" strike to remove a future threat.

"In either scenario, we can expect that attacking North Korea, even with an intended 'surgical strike,' will bring retaliation, most likely against South Korean and American forces and civilians on the Korean peninsula ? there are a lot of both within range of North Korean missiles and artillery ? and possibly a second Korean War," Galluci said.

"The US and its allies should be ready for this. At the moment, neither we nor our allies are prepared for war," he said.

Gallucci also rejected that tougher sanctions aren't likely to work either.

"The real alternative to war is a negotiated settlement that addresses the threat," he said.

Recalling the ultimate breakdown of the 1994 deal, Gallucci said that a new deal with the North should be made better than the last deal and should require that the North improve the human rights of its citizens as a condition of normalizing relations with the US. (Yonhap)