According to
wikipedia, the US proposed to the Soviets that Korea should be partitioned due to being spooked by just how rapidly the Soviets were advancing against the Japanese once they'd joined the Pacific war.
To the American's surprise, the Soviets accepted.
So WI they didn't?
Let's say that as per OTL, the Americans send the proposal to the Soviets on August 10th. The Soviets think for a while (as opposed to the immediate acceptance of OTL) but refuse before August 17th (allowing a different version of General Order No. 1 to be issued on time).
As per OTL, the Soviets arrive by amphibious landing in Korea by August 14 and rapidly take over the north-east of the country. By August 16 they land at Wonsan. By August 24, the Red Army reach Pyongyang.
Now, if the US isn't feeling secure about how much of the Korean pie they'll get, does the US arrive in the south on September 8th as per OTL, or earlier? If earlier, how much earlier can the US land, and how far North can the American forces make it before they hit the Soviet lines? If the US can't make it to Korea any sooner, how far South can the Soviets make it before the US arrives? Can the Soviets take the whole peninsula in time?
fasquardon