La locomotiva.

The private train North Korean leader Kim Jong-il uses on his trips either within the communist country or abroad consists of six around 90 carriages, and some 20 train stations have been built specifically for his own use. To defend Kim against attack, two separate trains precede and follow the main entourage, one handling reconnaissance and the other security.

(The Facts About Kim Jong-il's Private Train)
(Kim’s train stations (updated))