<P> After these reversals of fortune, which saw Seoul change hands four times, the last two years of fighting became a war of attrition, with the front line close to the 38th parallel . The war in the air, however, was never a stalemate . North Korea was subject to a massive bombing campaign . Jet fighters confronted each other in air - to - air combat for the first time in history, and Soviet pilots covertly flew in defense of their communist allies . </P> <P> The fighting ended on 27 July 1953, when an armistice was signed . The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners . However, no peace treaty has been signed, and according to some sources the two Koreas are technically still at war . </P> <P> As a war undeclared by all participants, the conflict helped bring the term "police action" into common use . It also led to the permanent alteration of the balance of power within the United Nations, where Resolution 377--passed in 1950 to allow a bypassing of the Security Council if that body could not reach an agreement--led to the General Assembly displacing the Security Council as the primary organ of the UN . </P> <Table> <Tr> <Td_colspan="2"> Korean War </Td> </Tr> <Tr> <Th_colspan="2"> South Korean name </Th> </Tr> <Tr> <Th> Hangul </Th> <Td> 한국 전쟁 </Td> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Th_colspan="2"> (show) Transcriptions </Th> </Tr> <Tr> <Th> Revised Romanization </Th> <Td> Hanguk Jeonjaeng </Td> </Tr> <Tr> <Th> McCune--Reischauer </Th> <Td> Han'guk Chŏnjaeng </Td> </Tr> </Table> </Td> </Tr> <Tr> <Th_colspan="2"> North Korean name </Th> </Tr> <Tr> <Th> Chosŏn'gŭl </Th> <Td> 조선 전쟁 </Td> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Th_colspan="2"> (show) Transcriptions </Th> </Tr> <Tr> <Th> Revised Romanization </Th> <Td> Joseon Jeonjaeng </Td> </Tr> <Tr> <Th> McCune--Reischauer </Th> <Td> Chosŏn Chŏnjaeng </Td> </Tr> </Table> </Td> </Tr> </Table>

Who declared war on north korea in 1950
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