(CNN) President Donald Trump has issued an executive order banning travel to the US from seven Muslim-majority countries.

The order has caused confusion at the nation's airports as some people from those countries were detained as they arrived in the US. The move also has been met with legal challenges and street protests across America.

Here are the latest developments:

Confusion over the executive order

Trump administration officials seemed at times to contradict themselves during appearances on Sunday news shows. On NBC, White House chief of staff Reince Priebus said the order "doesn't affect" green card holders, then later said "of course" it affects green card holders from Iran, Iraq, Syria, Sudan, Libya, Yemen and Somalia -- the seven countries that Trump has banned immigration from for 90 days.

Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina released a joint statement Sunday saying: "Our government has a responsibility to defend our borders, but we must do so in a way that makes us safer and upholds all that is decent and exceptional about our nation.

Trump's immigration order: Which countries are affected? Iran

Iraq

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"It is clear from the confusion at our airports across the nation that President Trump's executive order was not properly vetted. We are particularly concerned by reports that this order went into effect with little to no consultation with the Departments of State, Defense, Justice, and Homeland Security," they added.

"This executive order sends a signal, intended or not, that America does not want Muslims coming into our country. That is why we fear this executive order may do more to help terrorist recruitment than improve our security."

Attorneys general from 15 states and the District of Columbia issued a joint statement condemning what they called an "unconstitutional, un-American and unlawful Executive Order." The statement was issued by the attorneys general of New York state, California, Pennsylvania, Washington state, Massachusetts, Hawaii, Virginia, Oregon, the District of Columbia, Connecticut, Vermont, Illinois, New Mexico, Iowa, Maine and Maryland.

"As the chief legal officers for over 130 million Americans and foreign residents of our states, we ... will work together to ensure the federal government obeys the Constitution, respects our history as a nation of immigrants, and does not unlawfully target anyone because of their national origin or faith," they said in the statement.

"We are confident that the Executive Order will ultimately be struck down by the courts. In the meantime, we are committed to working to ensure that as few people as possible suffer from the chaotic situation that it has created."

Also, British Prime Minister Theresa May ordered the nation's foreign secretary and home secretary to hold talks with their US counterparts "to protect the rights of British nationals."

Protests continue

Meanwhile, for a second consecutive day, protesters were rallying across the country against President Trump's immigration policies.

Throngs of people gathered Sunday afternoon outside the White House. Crowds also formed in Boston's Copley Square, at Battery Park in Manhattan and at airports in Atlanta, Los Angeles, Washington and Dallas, with more planned in other cities.

These follow demonstrations that erupted Saturday over Trump's travel ban.

In New York City, a large crowd gathered at JFK International Airport Saturday to protest the detention of two Iraqis who were later released. Several New York officials showed support for the protests.

"Mr. President, look at us," said US Rep. Nydia Velazquez, a New York Democrat. "This is America. What you have done is shameful. It's un-American." The protesters gathered in Terminal 4 at JFK and carried signs reading, "We are all immigrants!" and "No ban! No wall!"

Virginia Gov. Terry McAuliffe joined protesters Saturday at Dulles International Airport outside Washington, D.C. "This Executive Order is antithetical to the values that make America great, and it will make our country less safe," he said in a statement.

In Portland, Oregon, one demonstrator carried a sign that read, "Portland coffee comes from Yemen," one of the seven Muslim-majority nations on the no-travel list.

Details of the executive order

On Friday, Trump signed an order banning travel from seven Muslim-majority countries for 90 days and suspending all refugee admission for 120 days.

The countries affected are Iran, Iraq, Syria, Sudan, Libya, Yemen and Somalia, according to a White House official. It also caps the total number of refugees admitted into the United States during the 2017 fiscal year at 50,000, down more than half from the current level of 110,000.

"I am establishing new vetting measures to keep radical Islamic terrorists out of the United States of America," Trump said during the signing at the Pentagon. "We don't want them here."

JUST WATCHED Travel ban affects citizens of 7 Muslim-majority nations Replay More Videos ... MUST WATCH Travel ban affects citizens of 7 Muslim-majority nations 02:26

As of Saturday night, 109 people had not been allowed into the United States on the basis of the executive order, according to the Department of Homeland Security. It was unclear Sunday how many of those people were still being detained and how many had been sent back.

Pushback from the courts

A federal judge in New York granted an emergency stay Saturday night for citizens of the seven Muslim-majority countries who have already arrived in the United States and for those who are in transit and who hold valid visas. The judge ruled they cannot be removed from the US -- a decision that halts Trump's executive order barring citizens from those countries from entering the US for the next 90 days.

"The petitioners have a strong likelihood of success in establishing that the removal of the petitioner and others similarly situated violates their due process and equal protection guaranteed by the United States Constitution," US District Judge Ann Donnelly wrote in her decision.

"There is imminent danger that, absent the stay of removal, there will be substantial and irreparable injury to refugees, visa-holders, and other individuals from nations subject to the January 27, 2017, Executive Order," the ruling said.

The ACLU argued Saturday evening in federal court in New York for a nationwide stay that would block the deportation of all people stranded in US airports under what the organization called "President Trump's new Muslim Ban."

The civil rights group is representing dozens of travelers held at JFK International Airport Friday and Saturday, including two Iraqis with ties to the US military who had been granted visas to enter the United States.

The ruling does not necessarily mean the people being held at airports across the US are going to be released, said Zachary Manfredi of Yale's Worker and Immigrant Rights Advocacy Clinic, who helped draft the emergency stay motion. "The judge's order is that they (lawful visa/green card holders) not be removed from the US -- it doesn't immediately order that they be released from detention," he told CNN.

JUST WATCHED U.S. judge blocks deportations of banned travelers Replay More Videos ... MUST WATCH U.S. judge blocks deportations of banned travelers 01:02

In addition to Donnelly's ruling in New York:

--A federal court in Washington state has issued a stay forbidding travelers being detained there from being sent back to their home country. Meanwhile a federal court in Virginia has issued a temporary restraining order saying a group of 50 to 60 permanent residents returning from trips abroad should have access to lawyers while they are being detained at Dulles International Airport and that these residents cannot be removed from the United States for seven days.

--Federal judges in Boston ruled early Sunday that officials may not detain a person on the basis of President Trump's executive order. This ruling was made after the ACLU of Massachusetts filed a lawsuit asking for the release of two associate professors at the University of Massachusetts-Dartmouth, both Iranian nationals who are permanent residents of the United States.

The Department of Homeland Security said on Sunday it will comply with judicial orders not to deport detained travelers.

President Trump's comments

President Trump insisted Sunday that the ban would protect the United States from terrorists.

In an afternoon statement , Trump wrote the country would continue showing "compassion to those fleeing oppression."

"America has always been the land of the free and home of the brave," he wrote. "We will keep it free and keep it safe, as the media knows, but refuses to say."

He pushed back on criticism suggesting his executive order amounts to the "Muslim ban" he proposed as a candidate.

"To be clear, this is not a Muslim ban, as the media is falsely reporting," he wrote. "This is not about religion -- this is about terror and keeping our country safe."

Asked during a photo opportunity in the Oval Office Saturday afternoon about the rollout of the executive order, Trump said his government was "totally prepared."

"It's working out very nicely," Trump told reporters. "You see it at the airports. You see it all over. It's working out very nicely and we're going to have a very, very strict ban, and we're going to have extreme vetting, which we should have had in this country for many years."

JUST WATCHED Trump: Travel ban working out very nicely Replay More Videos ... MUST WATCH Trump: Travel ban working out very nicely 01:07

The policy team at the White House developed the executive order on refugees and visas, largely avoiding the traditional inter-agency process that would have allowed the Justice Department and Homeland Security agencies to provide operational guidance, according to numerous officials who spoke to CNN on Saturday.

Homeland Security Secretary John Kelly and Department of Homeland Security leadership saw the final details shortly before the order was finalized, government officials said.