There is a necessity to conduct "extreme vetting" of immigrants into the US to fight against radical Islam, Donald Trump has said.
The Republican presidential candidate said new arrivals should be tested to ascertain if they share Western values such as religious tolerance and the acceptance of LGBT rights.
The suggestion comes months after Trump first suggested a blanket ban on all Muslims entering the US until leaders could solve terrorism-related problems.
Speaking in Ohio, Trump said: "The time is overdue to develop a new screening test for the tests we face today. I call it "extreme vetting".
"We will have to temporarily suspend immigration from some of the most dangerous and volatile regions of the world that have a history of exporting terrorism.
"As soon as I take office I will ask the state department and department of homeland security to identify a list of regions where adequate screening cannot take place," Trump continued.
The test would also be used to "screen out any who have hostile attitudes toward our country or its principles or believe that Sharia law should supplant American law".
"Those who do not believe in our constitution, or who support bigotry and hatred, will not be admitted for immigration into our country.
"We cannot let this evil continue. Nor can we let the hateful ideology of radical Islam ... be allowed to spread within our own countries," Trump added, stating such measures are vital in order to stop the spread of the Islamic State (Isis).
"Isis is on the loose. Isis has spread across the Middle East and into the west. Today they are fully operational in 18 countries," he said, adding that Clinton lacks the mental and physical stamina to take on Isis.
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Meanwhile, Hillary Clinton, the billionaire's Democrat rival, said Trump would be unsuitable as commander-in-chief.
Her spokesperson said of Trump's speech: "This so-called 'policy' cannot be taken seriously."
"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?"
The speech comes after 50 Republican foreign policy experts blasted Trump by claiming he would be "the most reckless president" in US history.
"Trump has demonstrated repeatedly that he has little understanding of America’s vital national interests, its complex diplomatic challenges, its indispensable alliances, and the democratic values on which U.S. foreign policy must be based. At the same time, he persistently compliments our adversaries and threatens our allies and friends," they wrote earlier this month.