He points the finger at US President Donald Trump's speech to the UN, where he threatened to "utterly destroy" North Korea, saying it may "well come to be viewed as 'historic', but not in a good way".
"The strategic consequences of carrying out this threat, even if successful, will be felt for the remainder of this century, largely to the detriment of the United States and the western world," he writes.
The speech, he said, "undercut any possibility that North Korea would consider making any concession on its nuclear deterrent by underlining that the US will not keep its word even when it has negotiated an agreement with a hostile government".
DeThomas compares Trump to Germany's Kaiser Wilhelm II.
"Trump shares one common and dangerous trait with the Kaiser: both were amateur militarists given to public bluster and adopting an ultranationalist bullyboy style of diplomacy, in part to cover up vast weaknesses in their own characters and their lack of understanding of their countries' true strengths," he writes.
"But neither of these individuals intended to unleash catastrophe."
DeThomas argues that the "tense but stable" 64-year-old strategic environment on the Korean peninsula, where 25 million civilians in the Seoul metropolitan region are held hostage by North Korean artillery, rockets and missiles, has been up-ended by a "fatal error" in North Korean strategic calculation and a suddenly unpredictable US leader.
"Pyongyang has chosen to: 1) add millions of US hostages to its strategy by pressing forward with development of a thermonuclear-tipped ICBM; and 2) craft and test a nuclear war fighting strategy that targets nuclear weapons on key US military assets and facilities which are critical to US and ROK defence planning."
North Korea "probably believes" that once it has a viable ability to strike the US, it will be able to negotiate out of sanctions, and is hence "paradoxically racing towards the one condition" that would cause the US to strike.
"President Trump was not wrong in saying Kim Jong-Un was on a suicide mission,"
DeThomas writes, adding the situation is compounded by the Trump administration's "absolute passion for reneging on agreements", as North Korea is certain to be closely watching the fate of the Iran nuclear deal.
"If the Iran agreement is trashed, Kim Jong-Un would be a fool of the first order to negotiate any reduction in his deterrent with the US," he writes.
"In other words, in a nuclearised environment in which North Korea and the US have sound military reasons to want to attack first, Trump informed the North Koreans that he will not be bound by a diplomatic agreement and his military intent is the extinction of the DPRK. He has cornered a vicious animal and told it he intends to kill it and its young.
"We are not yet at the point of war, but the gears of war are beginning to grind inexorably towards it. The lamps are going out in Asia."
It comes as North Korea accuses the US of having already declared war, a claim rubbished by the White House as beyond absurd. According to retired US Air Force brigadier general Rob Givens, if war did break out, about 20,000 people a day would be killed, even before nuclear weapons entered the picture.
"Even without nukes it will be devastating," he told theLA Times.