On Sunday, President Trump issued a presidential proclamation banning or restricting travel from eight countries — adding Chad, Venezuela and North Korea to the original list of Iran, Libya, Somalia, Syria, and Yemen.

In March, Trump ordered a worldwide review the government’s vetting and screening procedures for people seeking entry into the United States. The original 90-day ban, which impacted six counties and went into effect in June after a U.S. Supreme Court ruling, expired Sunday.

In July, new requirements on information sharing and security were sent to foreign governments. Any country that did not meet the new standards was given 50 days to make improvements, according to senior government officials.

At first, the U.S. Department of Homeland Security (DHS) found that 16 countries did not meet the new requirements, but after extensive engagement and new information sharing agreements, that number was reduced to eight, according to a senior U.S. official.

The new travel restrictions went into effect immediately for those subject to the two earlier travel bans, and take effect October 18 for those added into Sunday’s proclamation. The restrictions are indefinite and subject to change.

What’s different?

The March executive order temporarily barred entry into the U.S. of citizens of six Muslim-majority nations — Iran, Libya, Somalia, Sudan, Syria and Yemen. That was challenged in the courts and went into partial effect in June after a prolonged legal battle. The March executive order itself, revoked and replaced a similar order issued in late January.

In June, the court ruled that the March ban had to include an exception for people who have what the court called “any bona fide relationship with a person or entity in the United States.” The new proclamation doesn’t specifically include an exception for bona fide relationships.

The previous order was a temporary, 90-day ban. The new restrictions are “conditions-based, not time-based,” according to officials.

The proclamation kept some level of restrictions on five of the original six countries, which include Iran, Libya, Syria, Yemen and Somalia. The U.S. government removed restrictions on Sudan, which was one of the original six countries.

Who is impacted?

The ban applies to citizens of the eight countries — Chad, Iran, Venezuela, Libya, North Korea, Somalia, Syria, and Yemen — but the restrictions vary from country to country. In addition, although nationals of Iraq will not be banned, they will be subject to additional scrutiny to ensure threatening actors do not enter the U.S., according to senior officials.

Restrictions or additional vetting were added for four new countries found not to meet the new standards, including Chad, North Korea and Venezuela and Iraq — which is a special case, according to a senior government official.

Chad: Entry into the U.S. by nationals of Chad as immigrants and as non-immigrants on business, tourist, and business-tourist visas is suspended. Although Chad is an important partner, especially in the fight against terrorists, the government of Chad does not adequately share public safety and terrorism-related information, according to a senior government official.

Iran: Entry into the U.S. of nationals of Iran as immigrants and as non-immigrants is suspended, except under valid student or exchange visitor visa — although, those visas applicants will be subject to enhanced screening and vetting requirements. According to U.S. government officials, Iran was included because it’s government regularly fails to cooperate with the U.S. in identifying security risks, is the source of significant terrorists threats and is a state-sponsor of terrorism.

Venezuela: Only entry into the U.S. of certain Venezuelan government officials and their immediate family members as non-immigrants on business, tourist and business-tourist visas is suspended. According to U.S. officials, the government of Venezuela is uncooperative in verifying whether its citizens pose national security or public safety threats.

Libya: Entry into the United States of nationals of Libya as immigrants and as non-immigrants on business, tourist, and business-tourist visas is suspended. Government officials also called Libya an “important partner” in the fight against terrorism, but said the country faces significant challenges in sharing information and does not fully cooperate when it comes to taking back deported nationals.

North Korea: The entry into the United States of nationals of North Korea as immigrants and non-immigrants is suspended. It was concluded that the government in North Korea does not cooperate with the U.S. government in any respect and fails to satisfy all information-sharing requirements.

Somalia: Entry into the U.S. of nationals of Somalia as immigrants is suspended, and non-immigrants traveling to the United States will be subject to enhanced screening and vetting requirements. Despite the fact that U.S. officials believe Somalia to be an important partner in the fight against terror, and satisfies the bare minimum of U.S. information-sharing requirements, the government in Somalia still has significant identity management deficiencies and is recognized as a terrorist safe haven, among other concerns.

Syria: Entry into the U.S. of nationals of Syria as immigrants and non-immigrants is suspended. The government in Syria regularly fails to cooperate with the U.S. government in identifying security risks, is the source of significant terrorist threats, has been designated as a state sponsor of terrorism, has significant inadequacies in identity management protocols and fails to share public safety and terrorism information, according to U.S. officials.

Yemen: Entry into the United States of nationals of Yemen as immigrants and non-immigrants on business, tourist and business-tourist visas is suspended, although U.S. officials believe that Yemen is also an important partner.

The ban does not apply to lawful permanent residents, those already in the U.S. on the effective date, those with valid visas on the effective date, dual citizens who are traveling on passports of a non-banned country, or those already granted asylum.

After Oct. 18, anyone seeking an exception will have to apply for a waiver or qualify through an exception in the actual text of the proclamation, which is not as broad as the Supreme Court exceptions to the previous order, according to a senior U.S. official.

What’s next?

Since this proclamation is not time-based, countries can be removed from the list, while other countries can be added, based on changes in conditions.

Acting Department of Homeland Security (DHS) Sec. Elaine Duke, in coordination with other cabinet officials, can recommend changes to the president on a rolling basis. DHS must also submit reports to the president every 180 days providing an update on the current status of each country.

On Monday, the Supreme Court removed cases related to the previous travel ban from its calendar. Arguments in the case were scheduled to be heard on October 10, but, the court instead instructed the parties in the cases, Trump v. International Refugee Assistance and Trump v. Hawaii, to file briefs addressing “whether, or to what extent” the latest proclamation renders the issue moot.

Jack Date, Adam Kelsey and Lauren Pearle contributed to this story.