Which part?
Korean War - Wikipedia
"As with the
aerial bombing campaigns over Germany and Japan in World War II, the nominal objective of the U.S. Air Force was to destroy North Korea's war infrastructure and
shatter their morale. After MacArthur was removed as Supreme Commander in Korea in April 1951, his successors continued this policy and ultimately extended it to all of North Korea.
[316] The U.S. dropped a total of 635,000 tons of bombs, including 32,557 tons of napalm, on Korea, more than during the whole Pacific campaign of World War II.
[317][318]
Almost every substantial building in North Korea was destroyed as a result.
[319][320] The war's highest-ranking U.S. POW, U.S. Major General
William F. Dean,
[321] reported that the majority of North Korean cities and villages he saw were either rubble or snow-covered wasteland.
[322][323] North Korean factories, schools, hospitals, and government offices were forced to move underground, and air defenses were "non-existent."
[318] In November 1950, the North Korean leadership instructed their population to build dugouts and mud huts and to dig underground tunnels, in order to solve the acute housing problem.
[324] U.S. Air Force 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."
[325]Pyongyang, which saw 75 percent of its area destroyed, was so devastated that bombing was halted as there were no longer any worthy targets.
[326][327] On 28 November, Bomber Command reported on the campaign's progress: 95 percent of Manpojin was destroyed, along with 90 percent of Hoeryong, Namsi and Koindong, 85 percent of Chosan, 75 percent of both Sakchu and Huichon, and 20 percent of Uiju. According to USAF damage assessments, "eighteen of twenty-two major cities in North Korea had been at least half obliterated."
[328] 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."
US military presence is reported here:
United States Forces Korea - Wikipedia
"USFK is the joint headquarters through which U.S. combat forces would be sent to the South Korea/US (ROK/U.S.)"
"With 37,500 American soldiers, sailors, airmen and Marines in South Korea, U.S. forces in South Korea are a major presence in the region and a key manifestation of the U.S."
Imagine Canada got literally flattened by Russia and the Russia put a load of troops permanently in Alaska. Wouldn't blame Canada for wanting to defend itself.