Otto Warmbier

Young Pioneer Tours has also updated its North Korea FAQ page, starting with its top question: "How safe is it?"

The 22-year-old student, who was freed last week after more than a year in North Korean detention, died Monday. Doctors said last week that he had "extensive loss of tissue" in all parts of his brain.

Otto Warmbier is said to have been in a coma since sometime after his sentencing in North Korea in March 2016. The American student was sentenced to a 15-year prison term after his arrest.

Otto Warmbier, a 21-year-old University of Virginia student, had attempted to steal a propaganda sign from his Pyongyang hotel. He was convicted of subversion. The White House called for his release.