Several sources, including the Washington Post piece linked in the Newswire article, have referred to the train used by the North Koreans to visit the Chinese as “armored”.
If you were not allowed anywhere near the equipment to inspect it, how would you know that was the case?
Very likely any train he used would be “armored”
Wikepedia on North Korean leaders trains.
It seems Stalin gave an armored train to Grandpa Kim Il Sung.
http://english.chosun.com/site/data/html_dir/2011/09/01/2011090100792.html
The only armored US railcar was the Ferdinand Magellan from 1942 onward.
In this age of satellite cameras that can read license plates, discovering armored railroad cars doesn;t seem that difficult.
Isn’t Dwight Eisenhowers train armored? The one that used to be or still is at the Green Bay Railway museum? Understood it is built to British specs.