WASHINGTON, United States — US President Donald Trump boasted Saturday that his “very strict” crackdown on Muslim immigration was working “very nicely,” amid mounting resistance to the order which has been branded by many as blatantly discriminatory.

In an executive order signed Friday, Trump halted the arrival of refugees for at least 120 days and imposed tough new controls on travelers from Iran, Iraq, Libya, Somalia, Syria and Yemen for the next three months.

“It’s working out very nicely. You see it at the airports, you see it all over,” Trump told reporters, after travelers from those countries were stopped from boarding US-bound planes, triggering angry protests.

READ: Trump’s ‘insulting’ travel ban hits hard

“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.”

His comments came as the order faced its first lawsuit, signaling a tough battle ahead in US courts.

The legal challenge was filed by the American Civil Liberties Union and other advocacy groups after two Iraqi men were detained Friday night at John F. Kennedy Airport in New York.

Several US airports were rocked by protests and arrests after the ban.

It was not immediately clear how many travelers got caught up in Trump’s crackdown, which he says is necessary to prevent “radical Islamic terrorists” from entering the United States.

The ban has also triggered a political backlash.

“To my colleagues: don’t ever again lecture me on American moral leadership if you chose to be silent today,” Connecticut Senator Chris Murphy, a Democrat, tweeted late Friday.

His tweet was accompanied by the now iconic photograph of Aylan Kurdi, a three-year-old Syrian boy whose body was washed up on a beach in Turkey in 2015 after a failed attempt to flee Syria’s brutal war to join relatives in Canada. CBB