Donald Trump unveiled a revamped travel ban on Sunday just as his controversial immigration order covering six Muslim-majority nations was coming to an end.
Citizens of seven countries will face new restrictions on entry to the US under a proclamation signed by the US President.
"Making America Safe is my number one priority. We will not admit those into our country we cannot safely vet," Mr Trump said in a tweet.
The new rules, which will affect the citizens of Chad, Iran, Libya, North Korea, Somalia, Syria, and Yemen, will go into effect on October 18.
Most citizens of these countries will be indefinitely banned from entering the US.
Venezuela was also added to the list, but a suspension of non-immigrant visas to its citizens applies only to senior government officials and their immediate families.
Iraqi citizens will not be subject to travel prohibitions but will face enhanced scrutiny or vetting.
The announcement comes the same day as Mr Trump’s temporary ban on visitors from six Muslim-majority countries is set to expire, 90 days after it went into effect.
That ban had barred citizens of Iran, Libya, Somalia, Sudan, Syria and Yemen who lack a "credible claim of a bona fide relationship with a person or entity in the United States" from entering the US. Restrictions on citizens from Sudan were lifted.
"As President, I must act to protect the security and interests of the United States and its people," reads the proclamation.
The addition of North Korea and Venezuela broadens the restrictions from the original, mostly Muslim-majority list.
"North Korea does not cooperate with the United States government in any respect and fails to satisfy all information-sharing requirements," the proclamation said.
An administration official, briefing reporters on a conference call, acknowledged that the number of North Koreans travelling to the United States now was very low.