SEOUL • As United States President Donald Trump threatens to destroy North Korea, even some of his closest aides have warned of the potentially disastrous effects of a war.
New research published on the 38 North website points to just how catastrophic the impact might be on the regime's neighbours.
If North Korean leader Kim Jong Un were to launch a nuclear attack on Seoul and Tokyo - both within striking distance of his weapons - as many as 2.1 million people could die and another 7.7 million could be injured, according to the 38 North report.
The analysis by Mr Michael Zagurek Jr, a consultant specialising in databases and computer modelling, is based on North Korea's current estimated weapons technology and bomb strength.
Mr Zagurek assumes that Mr Kim has a baseline arsenal of 20 to 25 warheads and the capacity to put them on ballistic missiles.
Concerns about a nuclear conflict in North Asia have increased as Mr Kim accelerates his programme of acquiring weapons capable of hitting continental US, and as Mr Trump threatens preemptive military action.
While the chance of a direct attack on US allies Japan and South Korea remains slim, Mr Zagurek said history was replete with miscalculation by "rational actors" during crisis situations.
North Korean Foreign Minister Ri Yong Ho last month said the regime's possible next steps include testing a hydrogen bomb over the Pacific Ocean.
According to Mr Zagurek, it is possible that another nuclear test, an intercontinental ballistic missile test, or a missile test that has the payload impact area too close to US bases in Guam might see Washington react with force.
US options could include attempting to shoot down the test missiles or possibly attacking the North's missile testing, nuclear-related sites, missile deployment areas or the Kim regime itself. In turn, the North Korean leadership might perceive such an attack as an attempt to remove the Kim family from power and, as a result, could retaliate with nuclear weapons, he added.
North Korea's older warheads have yields in the 15-25-kilotonne range, around the size of the bombs that devastated Hiroshima and Nagasaki in 1945.
Fatality estimates rise significantly if North Korea were able to strike with bombs similar to the one it tested on Sept 3, which had a likely yield of 108-205 kilotonnes, Mr Zagurek said.