The conflict claimed over three million lives and divided the Korean Peninsula along ideological lines . On June 25 , 1950 , a Soviet-sponsored DPRK invasion crossed the 38th parallel . The conflict , which claimed over three million lives and divided the Korean Peninsula along ideological lines , commenced on June 25 , 1950 , with a Soviet-sponsored DPRK invasion across the 38th parallel , and ended in 1953 after international intervention pushed the front of the war back to near the 38th parallel .