The court's much anticipated decision in the last case it heard this term reversed a series of lower court decisions that had struck down the ban as Illegal or unconstitutional.

Chief Justice John Roberts issued the opinion, supported by Justices Anthony Kennedy, Clarence Thomas, Samuel Alito and Neil Gorsuch. It said the president's proclamation is "squarely within the scope of presidential authority" in the Immigration and Nationality Act. 

In sharply worded dissent, Justice Sonia Sotomayor, joined by Justice Ruth Bader Ginsburg, said the court's decision "fails to safeguard" this nation's fundamental principle of religious liberty and "leaves undisturbed" a policy that "now masquerades behind a facade of national-security concerns."

Immediate reaction on Twitter included Trump's message: "SUPREME COURT UPHOLDS TRUMP TRAVEL BAN. Wow!"

Catholic reaction included this tweet from the Sisters of Mercy: "This decision is disappointing and runs counter to this country's founding principles and values. Upholding this travel ban only exacerbates the scapegoating and attacks already directed against vulnerable communities, including immigrants, Muslims and people of colour."

And John Gehring, Catholic program director at Faith and Public Life, tweeted: "Imagine a travel ban for people from countries with heavily Catholic populations. Irish Catholic immigrants were once demonized and viewed as a threat to democracy. SCOTUS ruling makes a mockery of our commitment to religious liberty."

The majority opinion in the case, Trump v. Hawaii, stressed that the president had "lawfully exercised the broad discretion granted to him" to suspend entry into the United States and added that the president "possesses an extraordinary power to speak to his fellow citizens and on their behalf."

It also countered the plaintiff's arguments that "this president's words strike at fundamental standards of respect and tolerance, in violation of our constitutional tradition," by noting that the issue before the court was not "whether to denounce the statements" but instead to review the significance of them as part of a presidential directive that is "neutral on its face, addressing a matter within the core of executive responsibility. In doing so, we must consider not only the statements of a particular president, but also the authority of the presidency itself."

The opinion also supported the administration's argument that the government had a legitimate national security interest, noting that the president had removed three Muslim-majority countries -- Iraq, Sudan and Chad -- from the list on the travel ban. It also said the president's order provided "numerous exceptions for various categories of foreign nationals" and also created a waiver program to "all covered foreign nationals seeking entry as immigrants or nonimmigrants."

"Under these circumstances, the government has set forth a sufficient national security justification to survive rational basis review," the court said.

When this case was argued before the court April 25, the majority of justices seemed to indicate they would uphold the president's ban.

The challengers to the ban -- Hawaii, several individuals and a Muslim group -- argued that Trump's policy was motivated by an antagonism toward Muslims and that it violated federal immigration law and the U.S. Constitution's prohibition on the government favoring one religion over another.

Trump has said the travel ban is necessary to protect the United States from terrorism by Islamic militants who could enter the U.S. The current version of the directive is indefinite about how long it will be in place and applies to travelers from five countries with predominantly Muslim populations: Iran, Libya, Somalia, Syria and Yemen. It also blocks travelers from non-Muslim countries: North Korea and some Venezuelan government officials and their families.

The president's first travel ban, issued right after he took office, was blocked by several U.S. courts. A few months later, a second version of the ban was similarly blocked by several lower courts but the Supreme Court voted last December to allow the policy to take effect until it heard oral arguments about it.

Catholic Church leaders expressed their objection to the travel ban in an amicus brief filed March 30 by the U.S. Conference of Catholic Bishops, Catholic Charities USA and Catholic Legal Immigration Network.

They said the ban singles out "populations of six overwhelmingly Muslim nations for sweeping immigration restrictions" that do not exist elsewhere in the world.

The brief said the president's order showed "blatant religious discrimination," which is "repugnant to the Catholic faith, core American values, and the United States Constitution." It also said the Supreme Court should relegate the order "to the dustbin of history, so it will do no further harm."

The Catholic groups said Trump's action posed a major threat to religious liberty and also failed the basic test of religious neutrality. If it stands, they said in the brief, it will prevent countless refugees from escaping persecution and starting a new life in this country with the help of church resettlement agencies.