The Trump administration is preparing to begin enforcing key elements of its revised travel ban at 8 p.m. Thursday in Georgia and across the nation, as allowed by the U.S. Supreme Court’s ruling this week.

With some important exceptions, the government will block travelers from six Muslim-majority countries for 90 days, suspend the nation's refugee resettlement program for 120 days and limit the number of refugees who may be brought here this fiscal year to 50,000. The court said those restrictions cannot be applied to people with a "bona fide relationship with a person or entity in the United States."

Such people must have a “close familial relationship,” meaning a parent — including a parent-in-law —  spouse, child, adult son or adult daughter, son-in-law, daughter-in-law or sibling, according to a U.S. State Department cable obtained by Reuters. The cable says this includes step relationships. Not included are grandparents, grandchildren, aunts, uncles, nieces, nephews, cousins, brothers-in-law, sisters-in-law, fiancés and any other “extended family members.”

A senior administration official told reporters in a conference call that Thursday night would be “business as usual for us” at the nation’s airports.

“We expect things to run smoothly,” he said. “And our people are well prepared for this. And they will handle the entry of people with visas professionally, respectfully and responsibly, as they have always done, with an eye toward ensuring the country is protected from persons looking to travel here to do harm.”

Civil and immigrant rights groups blasted the new guidelines Thursday.

“This guidance shows a cruel indifference to families, some already torn apart by war and horrifying levels of violence,” said Naureen Shah, Amnesty International USA’s senior director of campaigns. “It also defines close family relationships in a way that ignores the reality in many cultures, where grandparents, cousins, and in-laws are often extremely close. Separating families based on these definitions is simply heartless.”

Another senior administration official told reporters the travel ban will help prevent terrorist attacks in the U.S.

“As recent events have shown, we are living in a very dangerous time,” he said. “And the U.S. government needs every available tool to prevent terrorists from entering the country and committing acts of bloodshed and violence.”

Amnesty International is dispatching researchers to airports in New York City, Washington, D.C., and Los Angeles to monitor how the ban is being implemented and to help travelers who encounter any problems. Meanwhile, the Southern Poverty Law Center is helping schedule volunteers to be on the lookout for any trouble at Atlanta's airport.

Johnathan Smith, legal director of Muslim Advocates, called the new guidelines “bigoted, discriminatory, and fundamentally unfair.”

“Defining close family to exclude grandparents, cousins, and other relatives defies common sense; it also directly goes against the intent of the Supreme Court's order,” he said.

The State Department cable says the travel ban exemptions will also apply to people with a relationship to an entity in the U.S. that is “formal, documented and formed in the ordinary course, rather than for the purpose of evading” the travel ban. The cable gives some examples: foreign journalists with newsrooms in the U.S., foreign students who have been admitted to schools here and workers who have been offered jobs at American companies.

The executive order allows consular officers to grant waivers to travelers on a case-by-case basis under certain conditions, including when they are determined to not pose national security threats. Some examples: people who are seeking to enter the U.S. for "significant business or professional obligations;" infants, young children, adoptees and people needing urgent medical care; and travelers seeking to meet or do business with the U.S. government.