The White House announced on Tuesday that it is expanding its travel ban to include five more countries, including Syria, and imposing new limits on others.
The administration also fully restricted travel on people with Palestinian Authority-issued travel documents.
"It is the policy of the United States to protect its citizens from foreign nationals who intend to commit terrorist attacks, threaten our national security and public safety, incite hate crimes, or otherwise exploit the immigration laws for malevolent purposes," US President Donald Trump said in the proclamation.
"The United States must exercise extreme vigilance during the visa-issuance and immigration processes to identify, prior to their admission or entry into the United States, foreign nationals who intend to harm Americans or our national interests."
The proclamation includes exceptions for lawful permanent residents, existing visa holders and certain visa categories such as those for athletes and diplomats. A social media account linked to the White House said the expansion was to "protect the security of the United States".
The move is part of a continuing effort to tighten US entry standards for travel and immigration. It follows the arrest of an Afghan citizen suspected of carrying out a shooting of two National Guard troops the day before Thanksgiving.
In June, Mr Trump announced that citizens of 12 countries would be banned from entering the US and those from seven others would face restrictions. The decision resurrected a hallmark policy of his first term.
At the time, the ban included Afghanistan, Myanmar, Chad, the Republic of the Congo, Equatorial Guinea, Eritrea, Haiti, Iran, Libya, Somalia, Sudan and Yemen, and heightened restrictions on visitors from Burundi, Cuba, Laos, Sierra Leone, Togo, Turkmenistan and Venezuela.
On Tuesday, the list was expanded to include Burkina Faso, Mali, Niger, South Sudan and Syria.
Another 15 countries are being added to the list of those facing partial restrictions: Angola, Antigua and Barbuda, Benin, Cote d’Ivoire, Dominica, Gabon, Gambia, Malawi, Mauritania, Nigeria, Senegal, Tanzania, Tonga, Zambia and Zimbabwe.
