US Republican presidential nominee Donald Trump has said that he would enact "extreme vetting" of immigrants.
In a speech in Ohio, the candidate outlined his plans to combat Islamic extremism, including a new screening test for arrivals to the US.
Applicants will be tested to determine if they share Western liberal values like LGBT and religious tolerance.
Democratic rival Hillary Clinton poured scorn on his plan, labelling it a "cynical ploy".
"This so-called 'policy' cannot be taken seriously," said her spokesman.
"How can Trump put this forward with a straight face when he opposes marriage equality and selected as his running mate the man [Mike Pence] who signed an anti-LGBT law in Indiana?"
Under Mr Trump's plan, citizens from countries with a history of terror will be banned but it is not clear which nations.
In the speech, he did not lay out his own military strategy for defeating the so-called Islamic State.
But he did repeat his claim he was opposed to the Iraq War before it began, whichfact-checkers say is untrue.
And he said that the oil in Iraq should have been seized by the US government to prevent it from becoming the property of IS.
In his speech, Mr Trump promised to:
- Ban immigration from countries where terrorism is widespread and vetting is poor
- Make alliances with all countries fighting against terrorism
- Introduce an ideology test for new immigrants arriving to the US
- Keep Guantanamo Bay prison open
- Establish a presidential commission to investigate Islamic terror
- Work with Nato, despite previously calling it "obsolete"
The billionaire initially proposed a blanket ban on all Muslims but has changed it to one that is based on an unspecified list of countries that export terror.
The latest proposal includes creating an ideological test for immigrants entering the country, with questions addressing how each applicant views American values such as religious freedom, gender equality and gay rights.
"Those who do not believe in our Constitution, or who support bigotry and hatred, will not be admitted for immigration into the country," he said.