[25][26] Seoul was captured by the KPA on 28 June, and by early August, the Republic of Korea Army (ROKA) and its allies were nearly defeated, holding onto only the Pusan Perimeter in the peninsula's southeast.

UN forces broke out from the perimeter on 18 September, re-captured Seoul, and invaded North Korea in October, capturing Pyongyang and advancing towards the Yalu River—the border with China.

Combat ended on 27 July 1953 with the signing of the Korean Armistice Agreement, which allowed the exchange of prisoners and created a 4-kilometre (2.5 mi) wide Demilitarized Zone (DMZ) along the frontline, with a Joint Security Area at Panmunjom.

Explaining the choice of the 38th parallel, Rusk observed, "Even though it was further north than could be realistically reached by U. S. [sic] forces in the event of Soviet disagreement ... we felt it important to include the capital of Korea in the area of responsibility of American troops".

[citation needed] Insurgency reignited in the spring of 1949 when attacks by guerrillas in the mountainous regions (buttressed by army defectors and North Korean agents) increased.

[79] Stalin began a more aggressive strategy in Asia based on these developments, including promising economic and military aid to China through the Sino-Soviet Treaty of Friendship, Alliance and Mutual Assistance.

According to Barbara Barnouin and Yu Changgeng, Mao agreed to support Kim despite concerns of American intervention, as China desperately needed the economic and military aid promised by the Soviets.

On the eve of the war, KMAG commander General William Lynn Roberts voiced utmost confidence in the ROK and boasted that any North Korean invasion would merely provide "target practice".

[93] For his part, Syngman Rhee repeatedly expressed his desire to conquer the North, including when US diplomat John Foster Dulles visited Korea on 18 June.

Diplomat John Foster Dulles stated: "To sit by while Korea is overrun by unprovoked armed attack would start a disastrous chain of events leading most probably to world war.

[138][139] Acting on Acheson's recommendation, Truman ordered MacArthur, the Supreme Commander for the Allied Powers in Japan, to transfer matériel to the South Korean military, while giving air cover to evacuation of US nationals.

[149][150] After conferring with Mao that this would be MacArthur's most likely strategy, Zhou briefed Soviet and North Korean advisers of Lei's findings, and issued orders to PLA commanders to prepare for US naval activity in the Korea Strait.

The United States Air Force (USAF) interrupted KPA logistics with 40 daily ground support sorties, which destroyed 32 bridges, halting daytime road and rail traffic.

[153] On 27 August, 67th Fighter Squadron aircraft mistakenly attacked facilities in Chinese territory, and the Soviet Union called the Security Council's attention to China's complaint about the incident.

[164] By 15 September, the amphibious force faced few KPA defenders at Incheon: military intelligence, psychological warfare, guerrilla reconnaissance, and protracted bombardment facilitated a light battle.

[189] On 25 November, on the Korean western front, the PVA 13th Army Group attacked and overran the ROK II Corps at the Battle of the Ch'ongch'on River, and then inflicted heavy losses on the US 2nd Infantry Division on the UN forces' right flank.

[205] The PVA had outrun its logistics capability and thus were unable to press on beyond Seoul as food, ammunition, and matériel were carried nightly, on foot and bicycle, from the border at the Yalu River to the three battle lines.

[209] Following the failure of ceasefire negotiations in January, the United Nations General Assembly passed Resolution 498 on 1 February, condemning the PRC as an aggressor and calling upon its forces to withdraw from Korea.

While MacArthur felt total victory was the only honorable outcome, Truman was more pessimistic about his chances once involved in a larger war, feeling a truce and orderly withdrawal could be a valid solution.

The disastrous failure of the Fifth Phase Offensive (which Peng recalled as one of only four mistakes he made in his military career) "led Chinese leaders to change their goal from driving the UNF out of Korea to merely defending China's security and ending the war through negotiations".

[243] In the months after the Shenyang conference, Peng went to Beijing several times to brief Mao and Zhou about the heavy casualties and the increasing difficulty of keeping front lines supplied with basic necessities.

[271] Speaking on 4 April, US Secretary of Defense Chuck Hagel said that Pyongyang "formally informed" the Pentagon that it "ratified" the potential use of a nuclear weapon against South Korea, Japan and the US, including Guam and Hawaii.

While the White House agreed to secret peace talks, the plan was rejected because North Korea refused to discuss nuclear disarmament as part of the treaty.

For the initial months of the war, the P-80 Shooting Star, F9F Panther, Gloster Meteor, and other jets under the UN flag dominated the Korean People's Air Force (KPAF) propeller-driven Soviet Yakovlev Yak-9 and Lavochkin La-9s.

Because China deployed new armies to the Sino-Korean frontier, ground crews at the Kadena Air Base, Okinawa, assembled atomic bombs for Korean warfare, "lacking only the essential pit nuclear cores."

In September 1953, the Soviet government agreed to "cancel or postpone repayment for all ... outstanding debts", and promised to grant North Korea one billion rubles in monetary aid, industrial equipment and consumer goods.

China canceled North Korea's war debts, provided 800 million yuan, promised trade cooperation and sent in thousands of troops to rebuild damaged infrastructure.

South Korean anti-Americanism after the war was fueled by the presence and behavior of United States Forces Korea military personnel and U.S. support for Park's authoritarian regime, a fact still evident during the country's democratic transition in the 1980s.

Inside mainland China, the war improved the long-term prestige of Mao, Zhou, and Peng, allowing the Chinese Communist Party to increase its legitimacy while weakening anti-communist dissent.

These successes were contrasted with China's historical humiliations by Japan and by Western powers over the previous hundred years, highlighting the abilities of the PLA and the Chinese Communist Party.