The State Department has urged Americans to avoid all travel to North Korea, warning that US citizens making the trip risk long and "unduly harsh" imprisonment if they fall foul of laws in the hermit state.
At least 14 US citizens have been detained by Pyongyang over the past decade, according to Washington.
"The State Department strongly urges US citizens to avoid all travel to North Korea due to the serious risk of arrest and long-term detention under North Korea's system of law enforcement, which imposes unduly harsh sentences, including for actions that in the United States would not be considered crimes," according to a statement Monday.
In one recent well-publicized case, 21-year old American student Otto Warmbier was arrested in January for allegedly stealing a propaganda sign from a tourist hotel in Pyongyang. He was sentenced in March to 15 years' hard labor.
Last month North Korea sentenced a detained Korean-American, Kim Dong-Chul, to 10 years' hard labor on charges of subversion and espionage, China's official Xinhua news agency said.
"North Korea has detained those who traveled independently and those who were part of organized tours. Being a member of a group tour or using a tour guide will not prevent North Korean authorities from detaining or arresting you," the statement cautioned.
"Efforts by private tour operators to prevent or resolve past detentions of US citizens in the DPRK have not been successful."
The State Department went on to say that Americans traveling to North Korea, against the advice of the State Department, "should have no expectation of privacy".
"All electronic and multimedia devices including USB drives, CDs, DVDs, mobile phones, tablets, laptops, Internet browsing histories and cookies are subject to search for banned content," read the statement, which added a long list of actions seen as harmless in the US but which could be deemed serious offenses in North Korea.
"Possession of any media, either physical or electronic, criticizing the DPRK government or its leaders is considered a criminal act punishable by long-term detention in hard labor camps and heavy fines."
Other activities that could be "treated as crimes" include "showing disrespect" to the country's past or current leaders, "entering North Korea without proper travel documentation," and "proselytizing or carrying out religious activities."
In addition to imprisonment for activities which might be treated as criminal, "numerous foreigners have been held in North Korea for extended periods of time without being formally charged with any crimes," the State Department said.