China has far more air bases than it has aircraft, so that aircraft can be concentrated quickly in one area for combat operations. This is particularly the case in the coastal region opposite Taiwan. Chinese military air bases come in two sizes. Large ones have two runways, a battalion of infantry for security, and a battalion or two of short range cannon and missile anti-aircraft weapons. The big bases can support up to six regiments, but often have only two in peacetime. Smaller bases have one regiment in peacetime, and can support two. Many civilian airports are designated for military use, and have a few hundred security and administrative personnel assigned in peacetime. In wartime, these airports can support up to nine air regiments. Many smaller air bases have no air regiments assigned, and a hundred or so troops assigned as caretakers. When air regiments are flown in, maintenance, security and anti-aircraft troops arrive by truck or railroad. The air force is organized into air divisions, each with two regiments in peacetime, and three or more in wartime. The divisions have a lot of fixed facilities, for administration and maintenance. In wartime, a division is expected to send one of its regiments off to a more active front. Chinese air divisions can handle far more regiments (nine or more) in wartime, and train for that task in peacetime.