"Every installation, facility, and village in North Korea now becomes a military and tactical target." Stratemeyer sent orders to the Fifth Air Force and Bomber Command to "destroy every means of communications and every installation, factory, city, and village." On 5 November 1950, General Stratemeyer gave the following order to the commanding general of the Fifth Air Force: "Aircraft under Fifth Air Force control will destroy all other targets including all buildings capable of affording shelter."
In the wake of the Kanggye attack, FEAF began an intensive firebombing campaign that quickly incinerated multiple Korean cities. On 17 November 1950, General MacArthur told U.S. Ambassador to Korea John J. Muccio, "Unfortunately, this area will be left a desert." By "this area" MacArthur meant the entire area between "our present positions and the border."
In May 1951, an international fact finding team from East Germany, West Germany, China, and the Netherlands stated, "The members, in the whole course of their journey, did not see one town that had not been destroyed, and there were very few undamaged villages." On 25 June 1951, General O'Donnell, commander of the Far Eastern Air Force Bomber Command, testified in answer to a question from Senator John C. Stennis ("…North Korea has been virtually destroyed, hasn't it?): "Oh, yes; … I would say that the entire, almost the entire Korean Peninsula is just a terrible mess. Everything is destroyed. There is nothing standing worthy of the name … Just before the Chinese came in we were grounded. There were no more targets in Korea."
In August 1951, war correspondent Tibor Meráy stated that he had witnessed "a complete devastation between the Yalu River and the capital." He said that there were "no more cities in North Korea." He added, "My impression was that I am traveling on the moon because there was only devastation—every city was a collection of chimneys."
Napalm was widely used. In John Ford's 1951 documentary, This is Korea, footage of napalm deployment is accompanied by a voice-over by John Wayne saying, "Burn 'em out, cook 'em, fry 'em"; the New York Herald Tribune hailed "Napalm, the No. 1 Weapon in Korea". Winston Churchill, among others, criticized American use of napalm, calling it "very cruel", as the US/UN forces, he said, were "splashing it all over the civilian population", "tortur[ing] great masses of people". The American official who took this statement declined to publicize it.
The bombing campaign destroyed almost every substantial building in North Korea. The war's highest-ranking U.S. POW, U.S. Major General William F. Dean, reported that the majority of North Korean cities and villages he saw were either rubble or snow-covered wasteland. North Korean factories, schools, hospitals, and government offices were forced to move underground. In November 1950, the North Korean leadership instructed the population to build dugouts and mud huts and to dig tunnels, in order to solve the acute housing problem.
USAF General Curtis LeMay commented, "We went over there and fought the war and eventually burned down every town in North Korea anyway, some way or another, and some in South Korea, too."[23] Pyongyang, which saw 75 percent of its area destroyed, was so devastated that bombing was halted as there were no longer any worthy targets.[24][25] By the end of the campaign, US bombers had difficulty in finding targets and were reduced to bombing footbridges or jettisoning their bombs into the sea.
After running low on urban targets, U.S. bombers destroyed hydroelectric and irrigation dams in the later stages of the war, flooding farmland and destroying crops.
On 13 May 1953, 20 F-84s of the 58th Fighter Bomber Wing attacked the Toksan Dam, producing a flood that destroyed seven hundred buildings in Pyongyang and thousands of acres of rice. On 15–16 May, two groups of F-84s attacked the Chasan Dam. The flood from the destruction of the Toksan dam "scooped clean" 27 miles (43 km) of river valley. The attacks were followed by the bombing of the Kuwonga Dam, the Namsi Dam and the Taechon Dam. The bombing of these five dams and ensuing floods threatened several million North Koreans with starvation; according to Charles K. Armstrong, "only emergency assistance from China, the USSR, and other socialist countries prevented widespread famine."
North Korea ranks alongside Cambodia (500,000 tons), Laos (2 million tons), and South Vietnam (4 million tons) as among the most heavily-bombed countries in history, with Laos suffering the most extensive bombardment relative to its size and population.
The Republic of Korea Ministry of Defense estimated total South Korean civilian casualties for the entire Korean War at 990,968, of which 373,599 (37.7%) were deaths. For North Korea, the Ministry estimated 1,500,000 total civilian casualties, including deaths, injuries, and missing, but did not separately report the number of deaths.[32] The Ministry made no specific estimates for deaths from U.S. bombing. Armstrong estimated that 12–15 percent of the North Korean population (c. 10 million) was killed in the war, or approximately 1.2 million to 1.5 million people.[21] Armstrong did not separately determine how many of these deaths were among civilians or caused by U.S. bombing.
Armstrong states that the bombing had a profound, long-lasting impact on North Korea's subsequent development and the attitudes of the North Korean people, which "cannot be overestimated": "Russian accusations of indiscriminate attacks on civilian targets did not register with the Americans at all. But for the North Koreans, living in fear of B-29 attacks for nearly three years, including the possibility of atomic bombs, the American air war left a deep and lasting impression. The DPRK government never forgot the lesson of North Korea's vulnerability to American air attack, and for half a century after the Armistice continued to strengthen anti-aircraft defenses, build underground installations, and eventually develop nuclear weapons to ensure that North Korea would not find itself in such a position again. … The war against the United States, more than any other single factor, gave North Koreans a collective sense of anxiety and fear of outside threats that would continue long after the war's end." In the eyes of North Koreans as well as some observers, the U.S.' deliberate targeting of civilian infrastructure which resulted in the destruction of cities and high civilian death count, was a war crime.
https://en.wikipedia.org/wiki/Bombing_of_North_Korea