A beleaguered economy and an unstable North Korean won make foreign currencies a safer bet.
The ‘long overdue’ study comes as Pyongyang faces criticism over its weapons program.
Supply delays and transportation problems also hold up gravity fed water systems.
Sources say China could be putting the brakes on cross-border labor.
China joins the United States, Russia and 12 other U.N. Security Council members in adopting the measures.
Pyongyang also bans overseas travel as the US and South Korea hold military exercises.
The U.N. Security Council moves to curtail Pyongyang's illegal trading activities.