The United States has again put North Korea on its human trafficking watchlist.

In an annual report released Tuesday, the U.S. State Department had North Korea in its worst-offender category, reserved for countries making no attempt to address human trafficking. Sixteen other countries --- including Iran, Myanmar and Cuba --- received the same grade as North Korea.

The department criticized Pyongyang for failing to confirm or acknowledge its human trafficking violations and for neglecting to punish those involved with the crime.

North Korea has ranked at the bottom of the list since the State Department began issuing the report in 2003.