Query: What did the US Air Force's daytime attacks cause the KPA to do?
Context: The United States Air Force (USAF) interrupted KPA logistics with 40 daily ground support sorties that destroyed 32 bridges, halting most daytime road and rail traffic. KPA forces were forced to hide in tunnels by day and move only at night. To deny matériel to the KPA, the USAF destroyed logistics depots, petroleum refineries, and harbors, while the U.S. Navy air forces attacked transport hubs.