Such a conflict would likely result in "hundreds of thousands" killed and injured and there could be "far-reaching consequences" for the global economy, Malcolm Chalmers, Deputy Director-General of the Royal United Services Institute (RUSI), wrote in the analysis.
The author warns that taking into account the level of tensions between Washington and Pyongyang as well as the current impossibility of diplomatic alternatives, military measures could be taken by the US president. Trump and his advisers may wish to "resolve the issue sooner rather than later."
"War is now a real possibility. With North Korea making rapid progress in its missile and nuclear programs, time is not on diplomacy’s side," the report said.
According to Chalmers, the war could start in a number of ways. Pyongyang could attack first if it believed Washington was preparing an attack; or the US could launch an attack if the North fired missiles into the ocean near Guam or California.
Tensions on the Korean Peninsula remain unprecedented as Washington and Pyongyang continue their exchange of threats and bellicose statements.
'Erupting the Will for Revenge'
Meanwhile, a North Korean state-run outlet on Friday bashed the recent flight drill of US strategic bombers and fighters near the North Korean coast, calling it a "provocation," according to Yonhap.
Over the weekend, US Air Force B-1B Lancers and South Korean F-15 fighter escorts went north of the demilitarized zone dividing North and South Korea in a flight route and flew along North Korea's east coast.
On Tuesday, President Trump reiterated that the US is ready for the "military option" to resolve the crisis.
"We are totally prepared for the second option, not a preferred option. If we take that option, it will be devastating, I can tell you that, devastating for North Korea. That's called the military option," Trump said during a news conference at the White House's Rose Garden.