
A U.N. soldier (left) stands guard at prisoner of war enclosure where a great mass of communist troops line up after their capture somewhere in Korea on March 21, 1951. Source

Bomber Command planes of the U.S. Far East Air Forces rain tons of high demolition bombs on a strategic military target of the Chinese Communists in North Korea on January 18, 1951.
Incredible as this may sound, the US actually bombed every city, town and village in North Korea, leaving the greatest part of the surviving population homeless, and all the farms and food supplies destroyed with napalm. Unknown to most Americans, the US 'totally destroyed' North Korea. In its Korean War bombing campaign, the US 'burned down every town in North Korea'.[6]

Crew members of a marine battery launcher hold their ears and crouch to the ground as rockets are fired into the night sky.
Lastly, there is no doubt that the US used biological and chemical weapons on North Korea; compelling evidence is still being uncovered. An international commission began an investigation into the claims of biological warfare and found extensive evidence of anthrax, bubonic plague, encephalitis and yellow fever. "The long-suppressed Korean War report on U.S. use of biological weapons released at last. Written largely by the most prestigious British scientist of his day, the "Report of the International Scientific Commission for the Investigation of the Facts Concerning Bacterial Warfare in Korea and China" was effectively suppressed upon its release in 1952. Published now in text-searchable format, it includes hundreds of pages of evidence about the use of U.S. biological weapons during the Korean War, available for the first time to the general public."[7] You can download the full report here:[8]
Two Canadian researchers, Steven Endicott and Edward Hagerman of York University, published in 1998 conclusive evidence that the US used biological weapons extensively in Korea and then lied about it.[9][10] The Americans made extensive use of the talents of General Shiiro Ishi, head of Japan's infamous biological warfare program, exposing the Koreans to anthrax and much else. The US of course vehemently denied claims about the use of biological weapons in Korea but the available evidence has increased every year, and there is now overwhelming proof that the US unleashed massive amounts of biological pathogens on North Korea and on parts of China.
There is no doubt remaining whatever that the US inflicted massive biological warfare on the people, intending to exterminate the entire population of North Korea. This was LeMay attempting to accomplish by viruses and bacteria what could not be done with bombs and napalm. We have extravagant amounts of evidence to support the claim that Curtis LeMay should be recorded in history as one of the most depraved sociopathic genocidal killers of all time. Another fact that isn't well-known is that by 1950, CIA teams were running secret chemical tests, including the use of LSD, on North Korean prisoners of war hoping to achieve mind control, amnesia, or both, and all with the active cooperation of the "gold standard" FDA.
Still, researching this topic will mostly produce articles on "North Korea's Biological Weapons Programs". This is the same tactic the US used on Cuba: after launching repeated and devastating biological weapons attacks on that poor small country, the US media were full of reports about Cuba's biological weapons programs. PubMed tells us that the US may have done so "at a time of great military stress", and several websites tell us that the US had "No practical capabilities" for biological and chemical warfare during the time of the Korean war. In fact, almost everyone in the US has lied about this for 70 years.
NOTES
[1] Bombing of North Korea
[2] How the U.S. conducted biowarfare against North Korea
[3] The Korean War and US 'Total Destruction' Began 70 Years Ago
[4] Americans once carpet-bombed North Korea. It's time to remember that past
[5] Americans have forgotten what we did to North Korea
[6] Unknown to most Americans, the US 'totally destroyed' North Korea once before
[7] The long-suppressed Korean War report on U.S. use of biological weapons released at last
[8] Report of the International Scientific Commission on Bacterial Warfare in Korea and China
[9] The United States and Biological Warfare: Secrets from the Early Cold War and Korea
[10] Expert Exposes US Biological Warfare During Korean War