The U.S. State Department announced Wednesday a new travel restriction to the Democratic People's Republic of Korea (DPRK) due to "serious and mounting risk of arrest and long-term detention of U.S. citizens."

The U.S. citizens to travel to the DPRK will be required to obtain a special passport validation, granted under very limited circumstances, the U.S. State Department said in a statement.

The new travel restriction will take into effect on Sept.1, and those Americans currently in the DPRK are requested to depart before that day, the statement added.

The State Department had strongly warned Americans against traveling to the DPRK long before the introduction of the travel restriction.